twobyte

Twobyte is a term used in computing to refer to a unit of data consisting of two consecutive bytes, equivalent to 16 bits. It is not an official SI unit, but the phrase appears in technical writing to describe storage, fields, or values that occupy two bytes.

In binary terms, a two-byte value can be unsigned, ranging from 0 to 65,535, or signed, using two's complement, from -32,768 to 32,767. The interpretation depends on the data type and encoding. When two-byte values are serialized for storage or transmission, endianness matters: little-endian systems place the least significant byte first, while big-endian systems place the most significant byte first. This affects data interchange across architectures.

Common uses for twobyte values include short-length fields in network protocols, file formats, and programming languages. Many languages provide a 16-bit integer type (for example, short in C and Java). In practice, two-byte fields are widely found in protocols such as TCP/UDP port numbers and various header fields, as well as in legacy hardware with 16-bit data buses.

In text encoding, the concept of two-byte code units appears in UTF-16, where most common characters are represented by a single 2-byte unit, while some characters require two units (surrogate pairs). This makes twobyte a relevant notion in discussions of character encoding and data interchange.

See also: byte, bit, word, nibble, endianness, UTF-16, 16-bit architecture.