The decimal numeral system (also called base ten or occasionally denary) has ten as its base. It is the numerical base most widely used by modern civilizations. Decimal notation normally refers to a base-10 positional notation such as the Hindu-Arabic numeral system.
The binary number system, or base-2 number system, represents numeric values using two symbols: 0 and 1. The usual base-2 system is a positional notation with a radix of 2.