base 2 is a positional numeral system with two as its base. It uses 2 different digits for representing numbers. The digits for base 2 could be 0, and 1.

base 23 is a positional numeral system with twenty-three as its base. It uses 23 different digits for representing numbers. The digits for base 23 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f, g, h, i, j, k, l, and m.