When you write library code, you often have to write several functions that differ only between the types that are passed to the function; the routine action is the same, it's just the types that have changed. C++ provides templates to allow you to write more generic code; you write the routine using a generic type and at compile time the compiler will generate a function with the appropriate types. The templated function is marked as such using the template keyword and a list of parameters in angle brackets (<>) that give placeholders for the types that will be used. It is important to understand that these template parameters are types and refer to the types of the parameters (and return a value of the function) that will be replaced with the actual types used by calling the functions. They are not parameters of the function, and you do not (normally) provide them when you call the function.
It is best to explain template functions with an example. A simple maximum...