action, linking, and helping verbs

The three functional families a verb can belong to, based on the job it does in its clause.

An action verb expresses something the subject does (run, seasoned). A linking verb (also called a state-of-being verb) does not show action — it connects the subject to a word that renames or describes it, called the subject complement (The soup tasted salty). A helping verb (auxiliary verb) is attached in front of a main verb to build a tense, question, or negative (has finished, will go, does not know).

Examples

"is," "seems," and "tasted" (in the sense of "is") are linking verbs.
"have" in "have gone" is a helping verb.