Binary is a base-2 numeral system that uses two symbols, 0 and 1, to represent values. It represents numbers using a combination of 0s and 1s, with each place value representing a power of two and doubling in value. The binary alphabet uses 8 binary digits (0s and 1s) to represent each letter, with the place values doubling from 128, 64, 32, 16, 8, 4, 2, to 1.