What Is Binary Number?
Binary is a base-2 number system that represents every value using only the digits 0 and 1, unlike the base-10 (decimal) system most people use day to day. Each digit's position represents a power of 2 instead of a power of 10. Computers use binary internally because each digit maps directly onto a transistor's on/off state.
Example
The binary number 1011 equals 11 in decimal: (1×8) + (0×4) + (1×2) + (1×1) = 8 + 0 + 2 + 1 = 11.