|The base (or radix) of a number
system is the number of different symbols available to
represent any digit within that system.
For example, the decimal system (Base 10) has a radix of 10. Decimal uses different combinations of 10 symbols to represent any value (i.e. 0, 1, 2, 3, 4, 5, 6, 7, 8, 9).
Computers work using electronic circuits which can only be switched to be on or off, with no shades of meaning in between. When a key is pressed the keyboard characters and numbers have to be converted into a sequence of 1's and 0's so that the computer can open or close its electronic switches in order to process the data. Because only two possible symbols can be used this is called a Binary system. This system works to a base of 2.