API

An application programming interface is an interface or communication protocol between different parts of a computer program, or between separate computer programs, intended to interconnect those parts, and simplify the implementation and maintenance of software. An API may be for a web-based system, operating system, database system, computer hardware, or software library. APIs are most commonly made available via REST and application-specific APIs such as SMPP. An SMS API is an example of an API intended for use with SMS.