7bit

7bit refers to data that uses seven bits per character, allowing up to 128 distinct code points. This concept is most closely associated with ASCII, the foundational character encoding in early computing and networking, which maps common letters, digits, punctuation, and control codes into 7-bit values.

Historically, many computer systems and communications channels operated on 7-bit data paths. While 8-bit bytes later became standard, the idea of 7-bit cleanliness persisted, particularly for interoperability with equipment and protocols that could not reliably transport 8-bit data. In practice, content labeled as 7bit is expected to contain only 7-bit ASCII characters, with no bytes in the 128–255 range.

When 7-bit transport is insufficient—for example, when binary data or extended characters must be sent over a channel that allows only 7-bit data—encoding schemes are used to preserve data integrity. MIME, the standard for formatting multimedia messages on the Internet, defines several content-transfer-encoding methods, including 7bit, 8bit, quoted-printable, and base64. The 7bit encoding indicates that the payload contains only 7-bit ASCII characters and does not require special transfer encoding.

In modern systems, 7bit remains relevant mainly for legacy channels, simple text content, and compatibility with older mail and protocol requirements. Most contemporary text across the Internet uses 8-bit encodings or Unicode, but 7-bit ASCII remains a core subset that ensures broad interoperability.

See also: ASCII, ISO/IEC 646, UTF-8, MIME, Base64.