# Binary - Simple English Wikipedia, the free encyclopedia

**Binary** is base 2 number system. It is base 2 because it uses two possible numbers: 0 and 1. Decimal, the system most of the world uses for daily life, is a base 10 system – it uses 10 characters (0–9). When binary numbers are written, a subscript "(2)" is added to distinguish them from the same number in base 10.

Computers work in binary, because wires can store information in two different ways: by being powered, or not being powered. Sets of binary numbers can be used to represent any information, such as text, audio, or video.

## Number system

[change | change source]When being introduced to binary numbers, it helps to go back and think about how base 10 or decimal numbers work. Consider the number 1101_{(10)} (base 10). We identify this number as one-thousand, one-hundred, one because it has a 1 in the thousands place, a 1 in the hundreds place, and a 1 in the ones place. But since the places represent 8, 4, 2, and 1 in binary, instead of 1000, 100, 10, and 1, the value converted to decimal (base 10) would be 8 + 4 + 1 = 13_{(10)}.

For another example, the binary number 101_{(2)} is 5 in decimal. The bit on the right is 1 and has a value of 1 (2^0). The middle bit has a value of 2 (2^1 or just 2), but it is a 0, so it is not added. The bit on the left is 1 and has a value of 4 (2^2 or 2 * 2). The bits that are 1s have values of 1 and 4. 1 + 4 = **5**.

## Computers

[change | change source]All computers use binary at the lowest level. Most hard memory, like compact discs and DVDs, use binary to represent large files.

With computers, eight binary bits together is called a *byte*. The size of files is commonly measured in *kilobytes* or *megabytes* (sometimes in *gigabytes*). A kilobyte is 1000 bytes. A megabyte is 1000 kilobytes, a gigabyte is 1000 megabytes and a terabyte is 1000 gigabytes. Sometimes, it is easier to measure bytes in groups of 1024, since 1024 is a power of 2. There are 1024 bytes in a *kibibyte*, 1024 kibibytes in a *mebibyte*, and 1024 mebibytes in a *gibibyte*.

*.*

**Binary**