In Excel VBA, a function is similar to a procedure but the main purpose of the function is to accept a certain input from the user and return a value which is passed on to the main program to finish the execution. There are two types of functions, the built-in functions (or internal functions) and the functions created by the programmers, or simply called user-defined functions. We shall deal with built-in functions in this lesson and the user-defined functions in the next lesson.
