Binary Explained: How Computers Represent Data

Every piece of data a computer stores or processes, text, images, sound, ultimately comes down to binary: long strings of 1s and 0s. Understanding why computers use binary, and how bits build up into bytes, explains a lot about how digital devices actually work underneath.

What Is Binary?

Binary is a base-2 number system, using only the digits 0 and 1. Each digit is called a bit, the smallest unit of digital information. As covered in Bytes, KB, MB, GB and TB Explained, 8 bits make up 1 byte, the standard unit computers use to measure and address data.

Why Computers Use Binary

Digital circuits are built to reliably distinguish between two states, current flowing or not, voltage high or low. Binary’s two digits map directly onto that physical reality, which is why it became the natural foundation for digital computing rather than, say, a base-10 system.

Worked Example

Common Mistakes

• Reading a binary number as if it were decimal. “101010” in binary is 42, not “one hundred one thousand ten.”
• Losing track of leading zeros. A byte is always 8 bits; “1010” as a full byte is written 00001010, not just 1010, since the leading zeros matter for a fixed-width representation.
• Assuming binary is only for numbers. Binary represents all digital data, text, images, and sound are all ultimately sequences of bits too, interpreted according to whatever format is being used.

Use the Binary Converters

The Binary to Text Converter and Text to Binary Converter convert between binary and plain text instantly. For a more compact way of writing the same binary data, see Hexadecimal Explained.