APIs, or Application Programming Interfaces, are tools that enable different software programs to communicate with each other. But what we typically think of as an API is the actual program itself, bundled with the the tools which enable the communication with it.

There are several types of APIs, each with its own use cases and features and a lot of what we’ll cover in this course could be applied to different types of APIs..if you think of things like security, optimization, or error handling. These are much the same no matter what type of API you create.

But our main focus will be on REST because that is by far what is most commonly created and consumed by PHP developers. It is knowledge and experience that the industry expects us to have whereas the other types are more likely to be considered nice to have.

REST on its own is a very big subject which is highly nuanced.