It is not easy to classify program interfaces, because there are thousands of them. In the context of mobile applications, we are most often talking about APIs written by backend programmers.

To make things a bit clearer, let’s look at a couple of examples of using APIs for mobile applications.
For example, the API of the Twitter application gives the application information about the user’s tweets and followers.

If we explain the essence of API in simple words, it is an “intermediary” between the software on the user’s device and an external platform (server, database, etc.).