Type

A type is a formal designation of what kind of data a given item is. For instance, it might be a number, or a character. Types usually include more specific details; e.g. for numbers, they might be signed or unsigned, floating point or integer, and there is usually an indication of the precision (i.e. number of bits).

The hardware usually supports a limited, fixed number of types, but the software may augment that set; e.g. FORTRAN supports complex numbers natively.

The use of structures or similar mechanisms may allow a programming language to support even more complex types; e.g. the 'BIGNUM' subroutine package of LISP allows the use of arbitrary precision integers.