Type

Type has historically had the following uses:

In computing, the datatype (sometimes called simply type) of an object depends on its classifier. In object-oriented programming, it became useful to distinguish an abstract data type from an implemented datatype.

In the decades of the 1900s and 1910s, in philosophy, Bertrand Russell used his theory of types to further discuss the mapping of mathematics to logic. See Principia Mathematica

In the development of printing, type was used for the metal forms of the letters used in typesetting. See, for example, typewriter.

In set theory and musical set theory, see equivalence class.