Browse Definitions :
Definition

bit (binary digit)

What is a bit (binary digit)?

A bit (binary digit) is the smallest unit of data that a computer can process and store. A bit is always in one of two physical states, similar to an on/off light switch. The state is represented by a single binary value, usually a 0 or 1. However, the state might also be represented by yes/no, on/off or true/false. Bits are stored in memory through the use of capacitors that hold electrical charges. The charge determines the state of each bit, which, in turn, determines the bit's value.

Although a computer might be able to test and manipulate data at the bit level, most systems process and store data in bytes. A byte is a sequence of eight bits that are treated as a single unit. References to a computer's memory and storage are always in terms of bytes. For example, a storage device might be able to store 1 terabyte (TB) of data, which is equal to 1,000,000 megabytes (MB). To bring this into perspective, 1 MB equals 1 million bytes, or 8 million bits. That means a 1 TB drive can store 8 trillion bits of data.

How a bit works

Each bit in a byte is assigned a specific value, which is referred to as the place value. A byte's place values are used to determine the meaning of the byte as a whole, based on the individual bits. In other words, the byte values indicate what character is associated with that byte.

A place value is assigned to each bit in a right-to-left pattern, starting with 1 and increasing the value by doubling it for each bit, as described in this table.

Bit position (right to left) Place value

Bit 1

1

Bit 2

2

Bit 3

4

Bit 4

8

Bit 5

16

Bit 6

32

Bit 7

64

Bit 8

128

The place values are used in conjunction with the bit values to arrive at the byte's overall meaning. To calculate this value, the place values associated with each 1 bit are added together. This total corresponds to a character in the applicable character set. A single byte can support up to 256 unique characters, starting with the 00000000 byte and ending with the 11111111 byte. The various combinations of bit patterns provide a range of 0 to 255, which means that each byte can support up to 256 unique bit patterns.

For example, the uppercase "S" in the American Standard Code for Information Interchange (ASCII) character set is assigned the decimal value of 83, which is equivalent to the binary value of 01010011. This figure shows the letter "S" byte and the corresponding place values.

the letter
Diagram illustrating the letter

The "S" byte includes four 1 bits and four 0 bits. When added together, the place values associated with 1 bits total 83, which corresponds to the decimal value assigned to the ASCII uppercase "S" character. The place values associated with the 0 bits are not added into the byte total.

Because a single byte supports only 256 unique characters, some character sets use multiple bytes per character. For example, Unicode Transformation Format character sets use between 1 and 4 bytes per character, depending on the specific character and character set. Despite these differences, however, all character sets rely on the convention of 8 bits per byte, with each bit in either a 1 or 0 state.

The term octet is sometimes used instead of byte, and the term nibble is occasionally used when referring to a 4-bit unit, although it's not as common as it once was. In addition, the term word is often used to describe two or more consecutive bytes. A word is usually 16, 32 or 64 bits long.

In telecommunications, the bit rate is the number of bits that is transmitted in a given time period, usually as the number of bits per second or some derivative, such as kilobits per second.

See also: most significant bit or byte, bitwise, bit stuffing, bit rot, bit slicing, qubit, how many bytes for and classical computing.

This was last updated in June 2022

Continue Reading About bit (binary digit)

SearchNetworking
  • network packet

    A network packet is a basic unit of data that's grouped together and transferred over a computer network, typically a ...

  • virtual network functions (VNFs)

    Virtual network functions (VNFs) are virtualized tasks formerly carried out by proprietary, dedicated hardware.

  • network functions virtualization (NFV)

    Network functions virtualization (NFV) is a network architecture model designed to virtualize network services that have ...

SearchSecurity
  • data breach

    A data breach is a cyber attack in which sensitive, confidential or otherwise protected data has been accessed or disclosed in an...

  • insider threat

    An insider threat is a category of risk posed by those who have access to an organization's physical or digital assets.

  • data compliance

    Data compliance is a process that identifies the applicable governance for data protection, security, storage and other ...

SearchCIO
  • data privacy (information privacy)

    Data privacy, also called information privacy, is an aspect of data protection that addresses the proper storage, access, ...

  • leadership skills

    Leadership skills are the strengths and abilities individuals demonstrate that help to oversee processes, guide initiatives and ...

  • data governance policy

    A data governance policy is a documented set of guidelines for ensuring that an organization's data and information assets are ...

SearchHRSoftware
SearchCustomerExperience
  • recommerce

    Recommerce is the selling of previously owned items through online marketplaces to buyers who reuse, recycle or resell them.

  • implementation

    Implementation is the execution or practice of a plan, a method or any design, idea, model, specification, standard or policy for...

  • first call resolution (FCR)

    First call resolution (FCR) is when customer service agents properly address a customer's needs the first time they call.

Close