The API can be compared with a waiter in a restaurant - it serves as a mediator between the one who orders food and the kitchen that prepares it. It delivers the order to the kitchen and then brings the dish to the client. The more customers there are in a restaurant, the more waiters are needed. In the same way, and as a rule, various people are involved in the development of the client and server. These are the Front-end and the Back- end Developers, each of which may use a different programming language.