Boolean Algebra

Forget the infinite number line — here every variable is either 0 (false) or 1 (true), and that's it. With just three operations — AND (∧), OR (∨), and NOT (¬) — you can express any logical condition, and a small set of algebraic identities lets you simplify it the way you'd simplify a polynomial. This two-valued algebra is the mathematical bedrock under every digital circuit and every if-statement you've ever written.