Binary is base-2: every digit is either 0 or 1, and each position represents a power of 2. It is the native language of digital electronics and CPU instructions.

Bitwise operators work directly on the binary representation: AND keeps a 1 only if both inputs have a 1 in that position; OR keeps a 1 if either does; XOR keeps a 1 if exactly one does. Shifts move bits left or right by N places, multiplying or dividing by 2^N.