There are many kinds and types of application programming interfaces (APIs). This book will only concentrate on a short list of them and this chapter is meant to get everyone on the same page.
What Is Understood as an API
Let me start with a statement that concentrates on the I of API, which, at least for me, is the most important piece:
An interface is a well-defined entry point into a system.
Here are a few examples of interfaces in different contexts:
An electrical socket: There is a socket and a plug. The plug goes into the socket, and the device connected to the socket works.
A vending machine ...
