What is an API and what is it for?
The purpose of an API is to decouple the backend of an application (e.g., a database) from the frontend (e.g., a web application or mobile application), as illustrated in Figure 2.1.
Figure 2.1 – Separation of concerns
The client does not talk directly to the database but rather talks to the API, which, in turn, talks to the database. The huge advantage of this approach is that you can modify the database and the client does not have to change. Alternatively, you can modify the front end (for example, a website) without changing the database.
These modifications take place throughout the development of a large project and continue after delivery. It is imperative, especially with a mobile application, that you can modify the backend without forcing the user to update the application. Even with web applications, however, this can be critical, as the team maintaining the database may well not be the team maintaining...
