Type parameter is a generic label used in generic programming to reference an unknown data type, data structure, or class. Type parameter is most frequently used in C++ templates and Java generics .
In most cases, type parameters have descriptive names, such as Key and Value in Dictionary<Key, Value> and Element in Array<Element>, which tells the reader about the relationship between the type parameter and the generic type or function it’s used in. However, when there isn’t a meaningful relationship between them, it’s traditional to name them using single letters such as T, U, and V.
The following are common letters to use:
* E for an element
* K for a map key
* V for a map value
* N for a number
* T for a generic data type
* S, U, V, and so forth for multiple generic types