Binary

Binary, term used to describe a place-value number system, or a number belonging to it, that uses 2 rather than the more common decimal system that uses 10 as its base. Each digit in a binary number represents a power of 2 and so can only hold a 0 or a 1. The number 2 functions in binary the way 10 functions in decimal numbers: each power of 2 reached—2 (2¹), 4 (2²), 8 (2³), …—requires an additional digit in binary just as each power of 10 reached—10 (10¹), 100 (10²), 1000 (10³), …—requires an additional digit in the decimal system. The binary numbers 1 to 8 are therefore written:

Decimal          Binary

(Base 10)       (Base 2)

1                    1

2                    10

3                    11

4                    100

5                    101

6                    110

7                    111

8                    1000

Most digital information, such as that stored on a computer’s hard drive, is in binary form.