In building applications, an API simplifies programming by abstracting the underlying implementation and only exposing objects or actions the developer needs. Recent developments in APIs have led to the rise in popularity of microservices, which are loosely coupled services accessed through public APIs. APIs originated in the 1940s, though the term did not emerge until the 1960s and 1970s. There are also APIs for programming languages, software libraries, computer operating systems, and computer hardware. The term API often refers to web APIs, which allow communication between computers that are joined by the internet. An API may be custom-built for a particular pair of systems, or it may be a shared standard allowing interoperability among many systems. One purpose of APIs is to hide the internal details of how a system works, exposing only those parts a programmer will find useful and keeping them consistent even if the internal details later change. An API specification defines these calls, meaning that it explains how to use or implement them. The calls that make up the API are also known as subroutines, methods, requests, or endpoints. A program or a programmer that uses one of these parts is said to call that portion of the API. An API is often made up of different parts which act as tools or services that are available to the programmer. It is not intended to be used directly by a person (the end user) other than a computer programmer who is incorporating it into the software. In contrast to a user interface, which connects a computer to a person, an application programming interface connects computers or pieces of software to each other. The term API may refer either to the specification or to the implementation.

A computer system that meets this standard is said to implement or expose an API. A document or standard that describes how to build or use such a connection or interface is called an API specification. It is a type of software interface, offering a service to other pieces of software. Screenshot of web API documentation written by NASAĪn application programming interface ( API) is a way for two or more computer programs to communicate with each other.

Java project hospital management system