A template in C++ is a feature that allows functions and classes to operate with generic types). It is a blueprint or formula for creating a generic class or function. Templates are a powerful tool in C++ that allows a function or class declaration to reference another different class (built-in or newly declared data type) without creating a full declaration for each of these different classes). Templates are expanded at compiler time, and the compiled code may contain multiple copies of the same function/class. There are three kinds of templates: function templates, class templates, and variable templates).

• Function templates: A function template is a generic function that can be used for different data types. Examples of function templates are sort(), max(), min(), and printArray().

• Class templates: A class template provides a specification for generating classes based on parameters. Class templates are generally used to implement containers, such as vector, LinkedList, and BinaryTree).

• Variable templates: In C++14, templates can also be used for variables).

To use templates, the keyword "template" is used in the syntax, followed by the data type variable defined by an angled bracket in a parameter (t). Templates can be used to construct a single function or single class that works with several data types. Templates are a very powerful feature of C++ that allows for generic programming, where generic types are used as parameters in algorithms to work for a variety of data types.