Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

self-information

How surprising a single outcome is, in bits — rarer outcomes carry more.

For an outcome $x$ with probability $p(x)>0$ , the self-information of $x$ is $I(x) = -\log p(x)$ .

Examples

A coin flip landing heads (p=0.5) carries $I=1$ bit; a 1-in-1000 event carries about 10 bits.