Logic Gates

Boolean algebra lives on paper — but logic gates make it physical. A gate is a tiny circuit that takes one or two signals (each a 0 or a 1, a low or high voltage) and outputs a single 0 or 1. AND, OR, and NOT gates implement the Boolean operations directly; XOR and NAND add two more. Wire enough of them together and you can add numbers, store memory, and run programs. This is, quite literally, how computers compute.