A bit (short for "binary digit") is the smallest unit of measurement used to quantify computer data. It contains a single binary value of 0 or 1.

While a single bit can define a boolean value of True (1) or False (0), an individual bit has little other use. Therefore, in computer storage, bits are often grouped together in 8-bit clusters called bytes. Since a byte contains eight bits that each have two possible values, a single byte may have 28 or 256 different values.

The terms "bits" and "bytes" are often confused and are even used interchangeably since they sound similar and are both abbreviated with the letter "B." However, when written correctly, bits are abbreviated with a lowercase "b," while bytes are abbreviated with a capital "B." It is important not to confuse these two terms, since any measurement in bytes contains eight times as many bits. For example, a small text file that is 4 KB in size contains 4,000 bytes, or 32,000 bits.

Generally, files, storage devices, and storage capacity are measured in bytes, while data transfer rates are measured in bits. For instance, an SSD may have a storage capacity of 240 GB, while a download may transfer at 10 Mbps. Additionally, bits are also used to describe processor architecture, such as a 32-bit or 64-bit processor.

Updated April 20, 2013 by Per C.

quizTest Your Knowledge

An asterisk (*) performs what mathematical function when used as an operator?

Correct! Incorrect!     View the Operator definition.
More Quizzes →

The Tech Terms Computer Dictionary

The definition of Bit on this page is an original definition written by the team. If you would like to reference this page or cite this definition, please use the green citation links above.

The goal of is to explain computer terminology in a way that is easy to understand. We strive for simplicity and accuracy with every definition we publish. If you have feedback about this definition or would like to suggest a new technical term, please contact us.

Sign up for the free TechTerms Newsletter

How often would you like to receive an email?

You can unsubscribe or change your frequency setting at any time using the links available in each email.

Questions? Please contact us.