Base-16 (also known as hexadecimal) number system uses 16 symbols to code information. Most commonly, these symbols are, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 'A to F' (or alternatively 'a to f').
Base-2 (also called binary) number system uses only two symbols to code information. Most commonly, these two symbols are, 0 and 1.