What is API, and what role does the general website setting API play?

Short message API (short message application program interface) is actually a set of definitions, programs and protocols, and the communication between computer software is realized through API interface. One of the main functions of API is to provide a general function set. Programmers using API functions to develop applications can avoid writing useless programs, thus reducing programming tasks. API is also a middleware, which provides data sharing for various platforms.