Wikipedia
In computer programming languages, '''TypeParameter''' is a frequently used generic label used in templates to reference an unknown data type, data structure, or class. Templates are most frequently used in Java and C++. TypeParameter is similar to a metasyntactic variable (e.g., foo and bar), but distinct. It is not the name of a generic variable, but the name of a generic type of variable.
The capitalisation varies according to programming language and programmer preference. TypeParameter, Typeparameter, TYPEPARAMETER, typeparameter, and type_parameter are all possible. Alternate labels are also used, especially in complex templates where more than one type parameter is necessary. X, Y, Foo, Bar, Item, Thing are typical alternate labels. Many programming languages are case-sensitive, making a consistent choice of labels important. The CamelCase TypeParameter is one of the most commonly used.