base 10 is a positional numeral system with ten as its base. It uses 10 different digits for representing numbers. The digits for base 10 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.

base 11 is a positional numeral system with eleven as its base. It uses 11 different digits for representing numbers. The digits for base 11 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and a.