You already know what a function is, but let’s give it a formal definition. A function is a body of code designed to solve a particular task. You should think of a function as a black box, the contents of which are unknown to you. All you care about is that it addresses some task to be accomplished in your program. Hundreds of functions are available for you to use in various function libraries. A function library is simply a collection of functions that share a common area of interest (e.g., the Math and Time functions in Arduino C.) However, many vendors have added new libraries of their own to support products and add-ons that they sell for the Arduino family. Functions make your life easier because you can stand on the shoulders of those who came before you. You can use their code rather than writing, testing, and debugging the code yourself.