Functions in Swift, Type of functions in Swift, @CharlesRealm : Explained

Explained a type of functions in swift and show how to use it.
Syntax of the function : how to declare the function, how to call the functions.
How to pass the value as a parameter to the functions.
Give label to the function.
Omitting label to the function
Give default value to the parameter
"inout" keyword in the function.