Rules & definitions reference

Formal. Each punctuation mark has one primary job. A period ends a statement. A comma separates items, sets off extra material, or joins clauses alongside a short joining word like and or but. A semicolon joins two independent clauses with no joining word at all, or separates items in a list that already contains commas. A colon announces a list, an explanation, or a quotation that follows. An apostrophe marks possession or a missing letter in a contraction. Quotation marks enclose exact spoken or quoted words, or a short title.

In plain English. If you had to pick one question each mark answers: period asks "is this sentence over?" Comma asks "does the reader need a tiny pause here?" Semicolon asks "are these two complete sentences close enough in idea to share one period?" Colon asks "am I about to hand the reader a list or an explanation?" Apostrophe asks "does something belong to something else, or is a letter missing?" Quotation marks ask "are these the exact words someone said or wrote?"

Breaking it apart. Period: ends a statement. Comma: separates, sets off, or joins with a short connecting word. Semicolon: joins two independent clauses directly, or separates a comma-heavy list. Colon: announces what comes next. Apostrophe: possession or contraction. Quotation marks: exact words or a short title.

Example. The committee reached one conclusion: the budget needed cuts. The colon announces the explanation that follows it, and that explanation could stand alone as its own sentence.

Non-example. The committee reached one conclusion, the budget needed cuts. Two independent clauses joined by only a comma. This is a comma splice; a colon, a semicolon, or a period would each fix it.

Why this rule exists. Every punctuation mark in English has a narrow, specific job. Confusing two marks' jobs, using a comma where a semicolon belongs, or a colon where a comma would do, is the single most common source of a punctuation error in student writing.

Formal. A proofreader's mark is a short, standardized abbreviation that flags one category of writing error. This course uses a fixed set, and every mark belongs to one of three families: word-level problems, sentence-boundary problems, and punctuation.

In plain English. A grader writes a few letters instead of a whole explanation, the way a doctor's chart says "BP" for blood pressure. Once you know the letters, you can read feedback in a second.

Breaking it apart.

• sp spelling; w.c. word choice; awk awkward, reword for clarity.
• frag fragment; r.o. run-on; c.s. comma splice. These three all ask where one sentence ends and the next begins.
• punc missing, wrong, or unnecessary punctuation; cap add or remove a capital letter.
• agr agreement: two words that should match in number don't.
• ^ a word or space is missing; ¶ start a new paragraph; X delete the marked text.

Example. I left, she stayed. gets c.s.: two complete sentences joined by only a comma.

Non-example. I left she stayed. is not c.s.. Nothing at all joins the two sentences, so it gets r.o..

Why this rule exists. Once you and a grader agree that frag always means the same thing, feedback stops depending on who happens to be reading your paper.

Formal. A dependent clause is a group of words containing a subject and a verb that cannot stand alone as a complete sentence — it depends on an independent clause to complete its meaning.

In plain English. It looks like a sentence because it has a subject and a verb, but it feels unfinished when you say it by itself. Something — usually a small word at the front — makes you expect more.

Breaking it apart. A dependent clause has the same subject-plus-verb shape as an independent one, but it opens with a subordinating conjunction (because, although, since, when, if, while, unless...) or a relative pronoun (who, which, that). That opening word is what creates the expectation the clause never finishes on its own.

Example. Because I was tired. Subject: I. Verb: was. But Because sets up "because ___, then ___" — you're left waiting for the rest.

Non-example. I was tired. Remove Because and the exact same subject-verb pair suddenly stands alone as a complete sentence — nothing else changed.

Why this definition exists. Punctuating a dependent clause as if it were a complete sentence is a fragment — one of the most common serious errors in student writing. Recognizing the subordinator is the one-second test that catches it every time.

Formal. An independent clause is a group of words that contains a subject and a verb and expresses a complete thought — it can stand alone as a sentence.

In plain English. It's a clause that doesn't need anything else. Say it out loud by itself and it sounds finished, not like you're waiting for more.

Breaking it apart. Three things have to be true at once: there's a subject (who or what), there's a verb (what the subject does or is), and together they say something complete — not "waiting for" anything else to follow.

Example. Shea's is a beautiful theater. Subject: Shea's. Verb: is. Complete thought: yes — nothing is missing.

Non-example. Because Shea's is a beautiful theater. Same subject and verb, but the word Because sets up an expectation the sentence never finishes — it needs another clause to complete it. That's a dependent clause, not an independent one.

Why this definition exists. Nearly every serious sentence-structure error in this course — a fragment, a run-on, a comma splice — is really just a question of how independent clauses were (or weren't) joined correctly. Getting this definition solid first is what makes every later rule make sense.

Formal. Every verb has four principal parts: the base form, the past tense, the past participle, and the present participle. A regular verb adds -ed for both the past and the past participle. An irregular verb forms its past, its past participle, or both some other way, so those two forms must be learned one verb at a time. The present participle (-ing) is always regular.

In plain English. The past stands alone (I went). The past participle never does: it follows has, have, or had (I have gone), or shows up when something is done to the subject (The pie was eaten). With an irregular verb, those two slots hold different words, so you have to pick.

Breaking it apart. The eight that cause the most trouble: go, went, gone; see, saw, seen; do, did, done; begin, began, begun; eat, ate, eaten; write, wrote, written; take, took, taken; drink, drank, drunk. A few verbs never change at all (cut, cut, cut).

Example. Yesterday I went home. I have gone home early all week. Went is the past, standing alone; gone follows have.

Non-example. I have went home. Went is the past, but have needs the past participle, gone.

Why this rule exists. For a regular verb the past and the past participle are the same word, so there's nothing to choose. The irregular verbs are the oldest, most-used words in English, and the mix-up between their two past forms is one of the most common verb errors in writing.

Formal. An independent clause is a group of words that contains a subject and a verb and expresses a complete thought — it can stand alone as a sentence.

In plain English. It's a clause that doesn't need anything else. Say it out loud by itself and it sounds finished, not like you're waiting for more.

Breaking it apart. Three things have to be true at once: there's a subject (who or what), there's a verb (what the subject does or is), and together they say something complete — not "waiting for" anything else to follow.

Example. Shea's is a beautiful theater. Subject: Shea's. Verb: is. Complete thought: yes — nothing is missing.

Non-example. Because Shea's is a beautiful theater. Same subject and verb, but the word Because sets up an expectation the sentence never finishes — it needs another clause to complete it. That's a dependent clause, not an independent one.

Why this definition exists. Nearly every serious sentence-structure error in this course — a fragment, a run-on, a comma splice — is really just a question of how independent clauses were (or weren't) joined correctly. Getting this definition solid first is what makes every later rule make sense.

Formal. An independent clause is a group of words that contains a subject and a verb and expresses a complete thought — it can stand alone as a sentence.

In plain English. It's a clause that doesn't need anything else. Say it out loud by itself and it sounds finished, not like you're waiting for more.

Breaking it apart. Three things have to be true at once: there's a subject (who or what), there's a verb (what the subject does or is), and together they say something complete — not "waiting for" anything else to follow.

Example. Shea's is a beautiful theater. Subject: Shea's. Verb: is. Complete thought: yes — nothing is missing.

Non-example. Because Shea's is a beautiful theater. Same subject and verb, but the word Because sets up an expectation the sentence never finishes — it needs another clause to complete it. That's a dependent clause, not an independent one.

Why this definition exists. Nearly every serious sentence-structure error in this course — a fragment, a run-on, a comma splice — is really just a question of how independent clauses were (or weren't) joined correctly. Getting this definition solid first is what makes every later rule make sense.

Formal. A dependent clause is a group of words containing a subject and a verb that cannot stand alone as a complete sentence — it depends on an independent clause to complete its meaning.

In plain English. It looks like a sentence because it has a subject and a verb, but it feels unfinished when you say it by itself. Something — usually a small word at the front — makes you expect more.

Breaking it apart. A dependent clause has the same subject-plus-verb shape as an independent one, but it opens with a subordinating conjunction (because, although, since, when, if, while, unless...) or a relative pronoun (who, which, that). That opening word is what creates the expectation the clause never finishes on its own.

Example. Because I was tired. Subject: I. Verb: was. But Because sets up "because ___, then ___" — you're left waiting for the rest.

Non-example. I was tired. Remove Because and the exact same subject-verb pair suddenly stands alone as a complete sentence — nothing else changed.

Why this definition exists. Punctuating a dependent clause as if it were a complete sentence is a fragment — one of the most common serious errors in student writing. Recognizing the subordinator is the one-second test that catches it every time.

Formal. English has exactly seven coordinating conjunctions — for, and, nor, but, or, yet, so — each joining two grammatically equal elements: two independent clauses, two words, or two phrases.

In plain English. FANBOYS is just a memory trick for the seven letters: For, And, Nor, But, Or, Yet, So. When one of these joins two complete sentences, it needs a comma in front of it.

Breaking it apart. Each one adds a slightly different relationship: for = because (reason), and = addition, nor = neither option, but = contrast, or = alternative, yet = contrast (like but), so = result. All seven can join two independent clauses the same structural way — comma before the conjunction.

Example. I wanted to go, but I was tired. Two independent clauses (I wanted to go / I was tired), joined by but with a comma before it — this is Structure #1, one of the five ways to build a compound or complex sentence.

Non-example. I wanted to go but I was tired. Same two clauses, same conjunction — missing only the comma. This is a run-on (the "second degree" kind), not a stylistic option: a coordinating conjunction joining two independent clauses always needs the comma before it.

Why this rule exists. FANBOYS is the single most common tool for building a compound sentence correctly, and forgetting the comma in front of it is one of the most common — and easiest to fix — punctuation errors in student writing.

Formal. A subordinating conjunction opens a dependent clause and names the exact relationship that clause has to the independent clause it attaches to. The common ones sort into four families by the relationship they signal: cause (because, since, as), contrast (although, though, even though, whereas, while), condition (if, unless, provided that), and time (when, after, before, until, once, as soon as).

In plain English. These are the words that turn a complete sentence into an unfinished one on purpose. "The store closed" stands alone. "Because the store closed" does not. The subordinator is what removes the clause's ability to stand by itself, and it also tells the reader exactly why the two ideas belong together: cause, contrast, condition, or time.

Breaking it apart. Cause words answer "why": because, since, as. Contrast words signal "but still": although, though, even though, whereas, while. Condition words set up an "if this, then that": if, unless, provided that. Time words place one event relative to another: when, after, before, until, once, as soon as.

Example. Although the store closed early, the manager stayed to finish the inventory. Although signals contrast: the store closing would normally mean everyone leaves, but the manager stayed anyway.

Non-example. The store closed early, the manager stayed to finish the inventory. Same two ideas, no subordinator and no coordinating conjunction either, just a comma. That is a comma splice, not a subordinated sentence.

Why this rule exists. A subordinator is doing two jobs at once: it marks the clause as dependent, and it names the logical relationship. Losing track of which family a subordinator belongs to is a common source of illogical sentences (using because where the relationship is actually contrast, for instance).

Formal. An independent clause is a group of words that contains a subject and a verb and expresses a complete thought — it can stand alone as a sentence.

In plain English. It's a clause that doesn't need anything else. Say it out loud by itself and it sounds finished, not like you're waiting for more.

Breaking it apart. Three things have to be true at once: there's a subject (who or what), there's a verb (what the subject does or is), and together they say something complete — not "waiting for" anything else to follow.

Example. Shea's is a beautiful theater. Subject: Shea's. Verb: is. Complete thought: yes — nothing is missing.

Non-example. Because Shea's is a beautiful theater. Same subject and verb, but the word Because sets up an expectation the sentence never finishes — it needs another clause to complete it. That's a dependent clause, not an independent one.

Why this definition exists. Nearly every serious sentence-structure error in this course — a fragment, a run-on, a comma splice — is really just a question of how independent clauses were (or weren't) joined correctly. Getting this definition solid first is what makes every later rule make sense.

Formal. English has exactly seven coordinating conjunctions — for, and, nor, but, or, yet, so — each joining two grammatically equal elements: two independent clauses, two words, or two phrases.

In plain English. FANBOYS is just a memory trick for the seven letters: For, And, Nor, But, Or, Yet, So. When one of these joins two complete sentences, it needs a comma in front of it.

Breaking it apart. Each one adds a slightly different relationship: for = because (reason), and = addition, nor = neither option, but = contrast, or = alternative, yet = contrast (like but), so = result. All seven can join two independent clauses the same structural way — comma before the conjunction.

Example. I wanted to go, but I was tired. Two independent clauses (I wanted to go / I was tired), joined by but with a comma before it — this is Structure #1, one of the five ways to build a compound or complex sentence.

Non-example. I wanted to go but I was tired. Same two clauses, same conjunction — missing only the comma. This is a run-on (the "second degree" kind), not a stylistic option: a coordinating conjunction joining two independent clauses always needs the comma before it.

Why this rule exists. FANBOYS is the single most common tool for building a compound sentence correctly, and forgetting the comma in front of it is one of the most common — and easiest to fix — punctuation errors in student writing.

Formal. Coordination joins two independent clauses in three standard ways (Structures #1-#3, forming a compound sentence); subordination joins one independent clause and one dependent clause in two ways (Structures #4-#5, forming a complex sentence). These five are the patterns for joining two clauses at a seam; adjective (relative) clauses and noun clauses also make complex sentences, but they sit inside the independent clause rather than meeting it at a seam, so they get no structure number. A colon (and, informally, a dash) can also join two independent clauses, but only when the second explains, illustrates, or completes the first; Chapter 13 covers those.

In plain English. There are five everyday patterns for hooking two clauses together at a seam with a conjunction or a conjunctive adverb. A clause tucked inside another one (the runner who finished first, I know that she left) is built differently and isn't one of the five. Learn these five, and "is this sentence built correctly?" stops being a guessing game.

Breaking it apart.

• #1 — independent clause + , + FANBOYS + independent clause
• #2 — independent clause + ; + independent clause
• #3 — independent clause + ; + conjunctive adverb + , + independent clause
• #4 — independent clause + subordinator + dependent clause (no comma; a trailing contrast clause with although, though, even though, or whereas usually takes one)
• #5 — subordinator + dependent clause + , + independent clause

Example, one of each.

• #1: Dr. Shock's face looked remarkable, for he had a single green eye.
• #2: I like horror movies; sometimes it's fun to be scared.
• #3: I like horror movies; however, I usually go to see dramas.
• #4: I like horror movies because they make my heart race.
• #5: Even though I usually go to see dramas, I like horror movies.

Non-example. Even though I usually go to see dramas. I like horror movies. This LOOKS like Structure #5 but uses a period where a comma belongs — a dependent clause can never be separated from its independent clause by a period or a semicolon. That's a fragment, not a sixth structure.

Why this rule exists. Whenever two clauses meet at a seam, the join should be one of these five patterns (or a colon or dash) — and nearly every comma splice, run-on, or fragment is what happens when a sentence tries to use a punctuation mark that belongs to a different one of the five.

Formal. A dependent clause is a group of words containing a subject and a verb that cannot stand alone as a complete sentence — it depends on an independent clause to complete its meaning.

In plain English. It looks like a sentence because it has a subject and a verb, but it feels unfinished when you say it by itself. Something — usually a small word at the front — makes you expect more.

Breaking it apart. A dependent clause has the same subject-plus-verb shape as an independent one, but it opens with a subordinating conjunction (because, although, since, when, if, while, unless...) or a relative pronoun (who, which, that). That opening word is what creates the expectation the clause never finishes on its own.

Example. Because I was tired. Subject: I. Verb: was. But Because sets up "because ___, then ___" — you're left waiting for the rest.

Non-example. I was tired. Remove Because and the exact same subject-verb pair suddenly stands alone as a complete sentence — nothing else changed.

Why this definition exists. Punctuating a dependent clause as if it were a complete sentence is a fragment — one of the most common serious errors in student writing. Recognizing the subordinator is the one-second test that catches it every time.

Formal. An independent clause is a group of words that contains a subject and a verb and expresses a complete thought — it can stand alone as a sentence.

In plain English. It's a clause that doesn't need anything else. Say it out loud by itself and it sounds finished, not like you're waiting for more.

Breaking it apart. Three things have to be true at once: there's a subject (who or what), there's a verb (what the subject does or is), and together they say something complete — not "waiting for" anything else to follow.

Example. Shea's is a beautiful theater. Subject: Shea's. Verb: is. Complete thought: yes — nothing is missing.

Non-example. Because Shea's is a beautiful theater. Same subject and verb, but the word Because sets up an expectation the sentence never finishes — it needs another clause to complete it. That's a dependent clause, not an independent one.

Why this definition exists. Nearly every serious sentence-structure error in this course — a fragment, a run-on, a comma splice — is really just a question of how independent clauses were (or weren't) joined correctly. Getting this definition solid first is what makes every later rule make sense.

Formal. A comma alone cannot join two independent clauses. Doing so produces a comma splice, a sentence-boundary error.

In plain English. A comma is a light, internal pause — it's not strong enough to glue two complete sentences together by itself. If you could put a period where the comma is and still have two real sentences, the comma alone isn't allowed to do that job.

Breaking it apart. Check both sides of the comma separately: could each one stand alone as its own sentence? If yes to both, the comma by itself is wrong. You need one of: a period, a semicolon, a comma plus a coordinating conjunction (FANBOYS), or a semicolon plus a conjunctive adverb and a comma.

Example of the error. Dr. Shock's face looked remarkable, he had a single green eye in the middle of his forehead. Both halves are complete sentences on their own — the comma alone can't join them.

Corrected three ways.

• Dr. Shock's face looked remarkable. He had a single green eye in the middle of his forehead. (period)
• Dr. Shock's face looked remarkable, for he had a single green eye in the middle of his forehead. (comma + FANBOYS)
• Dr. Shock's face looked remarkable; he had a single green eye in the middle of his forehead. (semicolon)

Non-example. Dr. Shock's face looked remarkable, and he had a single green eye in the middle of his forehead. This is not a comma splice — the comma is followed by and, a coordinating conjunction, which is exactly what a comma needs beside it to join two independent clauses.

Why this rule exists. A comma splice is one of the three sentence- boundary errors (with fragments and run-ons) that most reliably signal "not proofread" to a reader — and one of the easiest to fix once you can spot it.

Formal. Coordination joins two independent clauses in three standard ways (Structures #1-#3, forming a compound sentence); subordination joins one independent clause and one dependent clause in two ways (Structures #4-#5, forming a complex sentence). These five are the patterns for joining two clauses at a seam; adjective (relative) clauses and noun clauses also make complex sentences, but they sit inside the independent clause rather than meeting it at a seam, so they get no structure number. A colon (and, informally, a dash) can also join two independent clauses, but only when the second explains, illustrates, or completes the first; Chapter 13 covers those.

In plain English. There are five everyday patterns for hooking two clauses together at a seam with a conjunction or a conjunctive adverb. A clause tucked inside another one (the runner who finished first, I know that she left) is built differently and isn't one of the five. Learn these five, and "is this sentence built correctly?" stops being a guessing game.

Breaking it apart.

• #1 — independent clause + , + FANBOYS + independent clause
• #2 — independent clause + ; + independent clause
• #3 — independent clause + ; + conjunctive adverb + , + independent clause
• #4 — independent clause + subordinator + dependent clause (no comma; a trailing contrast clause with although, though, even though, or whereas usually takes one)
• #5 — subordinator + dependent clause + , + independent clause

Example, one of each.

• #1: Dr. Shock's face looked remarkable, for he had a single green eye.
• #2: I like horror movies; sometimes it's fun to be scared.
• #3: I like horror movies; however, I usually go to see dramas.
• #4: I like horror movies because they make my heart race.
• #5: Even though I usually go to see dramas, I like horror movies.

Non-example. Even though I usually go to see dramas. I like horror movies. This LOOKS like Structure #5 but uses a period where a comma belongs — a dependent clause can never be separated from its independent clause by a period or a semicolon. That's a fragment, not a sixth structure.

Why this rule exists. Whenever two clauses meet at a seam, the join should be one of these five patterns (or a colon or dash) — and nearly every comma splice, run-on, or fragment is what happens when a sentence tries to use a punctuation mark that belongs to a different one of the five.

Formal. English has exactly seven coordinating conjunctions — for, and, nor, but, or, yet, so — each joining two grammatically equal elements: two independent clauses, two words, or two phrases.

In plain English. FANBOYS is just a memory trick for the seven letters: For, And, Nor, But, Or, Yet, So. When one of these joins two complete sentences, it needs a comma in front of it.

Breaking it apart. Each one adds a slightly different relationship: for = because (reason), and = addition, nor = neither option, but = contrast, or = alternative, yet = contrast (like but), so = result. All seven can join two independent clauses the same structural way — comma before the conjunction.

Example. I wanted to go, but I was tired. Two independent clauses (I wanted to go / I was tired), joined by but with a comma before it — this is Structure #1, one of the five ways to build a compound or complex sentence.

Non-example. I wanted to go but I was tired. Same two clauses, same conjunction — missing only the comma. This is a run-on (the "second degree" kind), not a stylistic option: a coordinating conjunction joining two independent clauses always needs the comma before it.

Why this rule exists. FANBOYS is the single most common tool for building a compound sentence correctly, and forgetting the comma in front of it is one of the most common — and easiest to fix — punctuation errors in student writing.

Formal. Coordination joins two independent clauses in three standard ways (Structures #1-#3, forming a compound sentence); subordination joins one independent clause and one dependent clause in two ways (Structures #4-#5, forming a complex sentence). These five are the patterns for joining two clauses at a seam; adjective (relative) clauses and noun clauses also make complex sentences, but they sit inside the independent clause rather than meeting it at a seam, so they get no structure number. A colon (and, informally, a dash) can also join two independent clauses, but only when the second explains, illustrates, or completes the first; Chapter 13 covers those.

In plain English. There are five everyday patterns for hooking two clauses together at a seam with a conjunction or a conjunctive adverb. A clause tucked inside another one (the runner who finished first, I know that she left) is built differently and isn't one of the five. Learn these five, and "is this sentence built correctly?" stops being a guessing game.

Breaking it apart.

• #1 — independent clause + , + FANBOYS + independent clause
• #2 — independent clause + ; + independent clause
• #3 — independent clause + ; + conjunctive adverb + , + independent clause
• #4 — independent clause + subordinator + dependent clause (no comma; a trailing contrast clause with although, though, even though, or whereas usually takes one)
• #5 — subordinator + dependent clause + , + independent clause

Example, one of each.

• #1: Dr. Shock's face looked remarkable, for he had a single green eye.
• #2: I like horror movies; sometimes it's fun to be scared.
• #3: I like horror movies; however, I usually go to see dramas.
• #4: I like horror movies because they make my heart race.
• #5: Even though I usually go to see dramas, I like horror movies.

Non-example. Even though I usually go to see dramas. I like horror movies. This LOOKS like Structure #5 but uses a period where a comma belongs — a dependent clause can never be separated from its independent clause by a period or a semicolon. That's a fragment, not a sixth structure.

Why this rule exists. Whenever two clauses meet at a seam, the join should be one of these five patterns (or a colon or dash) — and nearly every comma splice, run-on, or fragment is what happens when a sentence tries to use a punctuation mark that belongs to a different one of the five.

Formal. A verb must agree in number with its true subject — singular with singular, plural with plural — regardless of any words that come between them.

In plain English. Find the real subject first, ignore whatever's sitting between the subject and the verb, and match the verb to that subject alone.

Breaking it apart. The trap is almost always a phrase sitting between subject and verb that has a different number than the real subject. The verb has to agree with the subject — never with the nearest noun.

Example. The box of old books is heavy. The subject is box (singular), not books (plural) — of old books is a prepositional phrase describing which box, not part of the subject. The verb agrees with box: is, not are.

Non-example. The box of old books are heavy. This is the exact error the rule guards against: the verb has agreed with books, the nearest noun, instead of box, the real subject.

Why this rule exists. Intervening phrases are the single most common source of subject-verb agreement errors — a writer's ear naturally matches the verb to whatever noun it just said, which is usually the wrong one.

Formal. Six English pronouns change form for case. The subject form performs the action of its clause (I, he, she, we, they, who). The object form receives the action of a verb or follows a preposition (me, him, her, us, them, whom). The choice depends on the pronoun's job in its own clause, never on where it sits in the sentence.

In plain English. Each of these pronouns has one form for doing the action and one for receiving it. She called the office, but The office called her. Ask what the pronoun is doing in its own small piece of the sentence.

Breaking it apart. The pairs, subject first: I/me, he/him, she/her, we/us, they/them, who/whom. To choose between who and whom, answer with he or him: he goes with who, him with whom (both end in -m). A preposition always takes the object form: to whom, between you and me.

Example. Whom did you thank? → You thanked him. → whom.

Non-example. Between you and I. Between is a preposition, so its object needs the object form: between you and me.

Why this rule exists. For ordinary sentences your ear gets case right. It fails in a few shapes, a pair of pronouns joined by and or a pronoun after a preposition, and those are where the errors cluster.

Formal. English has exactly seven coordinating conjunctions — for, and, nor, but, or, yet, so — each joining two grammatically equal elements: two independent clauses, two words, or two phrases.

In plain English. FANBOYS is just a memory trick for the seven letters: For, And, Nor, But, Or, Yet, So. When one of these joins two complete sentences, it needs a comma in front of it.

Breaking it apart. Each one adds a slightly different relationship: for = because (reason), and = addition, nor = neither option, but = contrast, or = alternative, yet = contrast (like but), so = result. All seven can join two independent clauses the same structural way — comma before the conjunction.

Example. I wanted to go, but I was tired. Two independent clauses (I wanted to go / I was tired), joined by but with a comma before it — this is Structure #1, one of the five ways to build a compound or complex sentence.

Non-example. I wanted to go but I was tired. Same two clauses, same conjunction — missing only the comma. This is a run-on (the "second degree" kind), not a stylistic option: a coordinating conjunction joining two independent clauses always needs the comma before it.

Why this rule exists. FANBOYS is the single most common tool for building a compound sentence correctly, and forgetting the comma in front of it is one of the most common — and easiest to fix — punctuation errors in student writing.

Formal. A dependent clause is a group of words containing a subject and a verb that cannot stand alone as a complete sentence — it depends on an independent clause to complete its meaning.

In plain English. It looks like a sentence because it has a subject and a verb, but it feels unfinished when you say it by itself. Something — usually a small word at the front — makes you expect more.

Breaking it apart. A dependent clause has the same subject-plus-verb shape as an independent one, but it opens with a subordinating conjunction (because, although, since, when, if, while, unless...) or a relative pronoun (who, which, that). That opening word is what creates the expectation the clause never finishes on its own.

Example. Because I was tired. Subject: I. Verb: was. But Because sets up "because ___, then ___" — you're left waiting for the rest.

Non-example. I was tired. Remove Because and the exact same subject-verb pair suddenly stands alone as a complete sentence — nothing else changed.

Why this definition exists. Punctuating a dependent clause as if it were a complete sentence is a fragment — one of the most common serious errors in student writing. Recognizing the subordinator is the one-second test that catches it every time.

Formal. Coordination joins two independent clauses in three standard ways (Structures #1-#3, forming a compound sentence); subordination joins one independent clause and one dependent clause in two ways (Structures #4-#5, forming a complex sentence). These five are the patterns for joining two clauses at a seam; adjective (relative) clauses and noun clauses also make complex sentences, but they sit inside the independent clause rather than meeting it at a seam, so they get no structure number. A colon (and, informally, a dash) can also join two independent clauses, but only when the second explains, illustrates, or completes the first; Chapter 13 covers those.

In plain English. There are five everyday patterns for hooking two clauses together at a seam with a conjunction or a conjunctive adverb. A clause tucked inside another one (the runner who finished first, I know that she left) is built differently and isn't one of the five. Learn these five, and "is this sentence built correctly?" stops being a guessing game.

Breaking it apart.

• #1 — independent clause + , + FANBOYS + independent clause
• #2 — independent clause + ; + independent clause
• #3 — independent clause + ; + conjunctive adverb + , + independent clause
• #4 — independent clause + subordinator + dependent clause (no comma; a trailing contrast clause with although, though, even though, or whereas usually takes one)
• #5 — subordinator + dependent clause + , + independent clause

Example, one of each.

• #1: Dr. Shock's face looked remarkable, for he had a single green eye.
• #2: I like horror movies; sometimes it's fun to be scared.
• #3: I like horror movies; however, I usually go to see dramas.
• #4: I like horror movies because they make my heart race.
• #5: Even though I usually go to see dramas, I like horror movies.

Non-example. Even though I usually go to see dramas. I like horror movies. This LOOKS like Structure #5 but uses a period where a comma belongs — a dependent clause can never be separated from its independent clause by a period or a semicolon. That's a fragment, not a sixth structure.

Why this rule exists. Whenever two clauses meet at a seam, the join should be one of these five patterns (or a colon or dash) — and nearly every comma splice, run-on, or fragment is what happens when a sentence tries to use a punctuation mark that belongs to a different one of the five.

Formal. A handful of word pairs account for most of the confused-word errors in student writing. They fall into three families: sound-alikes (spelled differently, pronounced almost identically), meaning-alikes (close enough in sense to swap by accident), and misheard phrases (a contraction that sounds like a different, wrong phrase).

In plain English. Its (belongs to it) versus it's (it is/it has). Your (belongs to you) versus you're (you are). Their (belongs to them), there (a place), and they're (they are). Affect (usually a verb, to influence) versus effect (usually a noun, a result). Imply (the speaker hints) versus infer (the listener concludes). Could of/should of/would of are never correct; the real word is always have (could have, should have, would have), misheard because have contracts to a sound that resembles of.

Breaking it apart. For every possessive-versus-contraction pair (its/it's, your/you're, their/they're), the test is the same: expand the contraction and see if the sentence still makes sense. "The dog wagged it is tail" fails, so its is correct there. For affect/effect: try substituting "influence" for the word in question; if that works, affect is right.

More pairs, one test each (Appendix A).

• Sound-alikes and look-alikes. Weather (rain, sun, wind) vs. whether (a choice): if if fits, write whether. Passed (the verb) vs. past (an earlier time, or "by"): if the sentence already has its own verb, write past. Lead (present, rhymes with seed; also the metal) vs. led (past tense of lead). Cite (name a source) vs. site (a place) vs. sight (seeing). Lose (misplace, not win) vs. loose (not tight). Advice and breath are things; advise and breathe are actions.
• Meaning-alikes. Amount goes with things you measure, number with things you count. Ensure = make sure an outcome happens; insure = protect with a policy; assure = calm a person (a person follows it). I.e. = "that is"; e.g. = "for example." Bring = toward the speaker; take = away. Can = ability; may = permission (the formal choice) or possibility.
• One word or two. All right is always safe; alright is informal. For/in/after a while takes two words; awhile means "for a while" and follows a verb. Everyday (one word) describes a noun, everyday shoes; every day means each day: if each day fits, write two words.

Example. Its tail wagged, and it's clear the dog was happy. The first its shows possession (the tail belongs to the dog); the second it's expands to "it is."

Non-example. Your going to love this, but you're book is on the table. Both swapped: you're (you are) is needed in the first spot, your (possession) in the second.

Why this rule exists. These pairs are spelled or pronounced closely enough that spell-check often can't catch the error. Each one is genuinely a different word doing a different job, and mixing them up is one of the fastest ways a piece of writing loses credibility with a careful reader.

Formal. Coordination joins two independent clauses in three standard ways (Structures #1-#3, forming a compound sentence); subordination joins one independent clause and one dependent clause in two ways (Structures #4-#5, forming a complex sentence). These five are the patterns for joining two clauses at a seam; adjective (relative) clauses and noun clauses also make complex sentences, but they sit inside the independent clause rather than meeting it at a seam, so they get no structure number. A colon (and, informally, a dash) can also join two independent clauses, but only when the second explains, illustrates, or completes the first; Chapter 13 covers those.

In plain English. There are five everyday patterns for hooking two clauses together at a seam with a conjunction or a conjunctive adverb. A clause tucked inside another one (the runner who finished first, I know that she left) is built differently and isn't one of the five. Learn these five, and "is this sentence built correctly?" stops being a guessing game.

Breaking it apart.

• #1 — independent clause + , + FANBOYS + independent clause
• #2 — independent clause + ; + independent clause
• #3 — independent clause + ; + conjunctive adverb + , + independent clause
• #4 — independent clause + subordinator + dependent clause (no comma; a trailing contrast clause with although, though, even though, or whereas usually takes one)
• #5 — subordinator + dependent clause + , + independent clause

Example, one of each.

• #1: Dr. Shock's face looked remarkable, for he had a single green eye.
• #2: I like horror movies; sometimes it's fun to be scared.
• #3: I like horror movies; however, I usually go to see dramas.
• #4: I like horror movies because they make my heart race.
• #5: Even though I usually go to see dramas, I like horror movies.

Non-example. Even though I usually go to see dramas. I like horror movies. This LOOKS like Structure #5 but uses a period where a comma belongs — a dependent clause can never be separated from its independent clause by a period or a semicolon. That's a fragment, not a sixth structure.

Why this rule exists. Whenever two clauses meet at a seam, the join should be one of these five patterns (or a colon or dash) — and nearly every comma splice, run-on, or fragment is what happens when a sentence tries to use a punctuation mark that belongs to a different one of the five.

Formal. English has exactly seven coordinating conjunctions — for, and, nor, but, or, yet, so — each joining two grammatically equal elements: two independent clauses, two words, or two phrases.

In plain English. FANBOYS is just a memory trick for the seven letters: For, And, Nor, But, Or, Yet, So. When one of these joins two complete sentences, it needs a comma in front of it.

Breaking it apart. Each one adds a slightly different relationship: for = because (reason), and = addition, nor = neither option, but = contrast, or = alternative, yet = contrast (like but), so = result. All seven can join two independent clauses the same structural way — comma before the conjunction.

Example. I wanted to go, but I was tired. Two independent clauses (I wanted to go / I was tired), joined by but with a comma before it — this is Structure #1, one of the five ways to build a compound or complex sentence.

Non-example. I wanted to go but I was tired. Same two clauses, same conjunction — missing only the comma. This is a run-on (the "second degree" kind), not a stylistic option: a coordinating conjunction joining two independent clauses always needs the comma before it.

Why this rule exists. FANBOYS is the single most common tool for building a compound sentence correctly, and forgetting the comma in front of it is one of the most common — and easiest to fix — punctuation errors in student writing.