What is an API in IT?

In computer science, API is the acronym for Application Programming Interface , which is translated into French as application programming interface or application programming interface . The API is an IT solution that allows applications to communicate with each other and to mutually exchange services or data.

Application programming interfaces generally offer a set of functions which facilitate, via a programming language making it possible to launch requests, access to the services of an application.

How does an API work?

An API makes it possible to access the functions or data of an application remotely, generally from another application, via a standard application interface. A request is sent to the target software in a universal language.

The API language, a sort of universal Esperanto, allows the requested software to understand what is requested, then to perform the actions and deliver the requested content (see diagram below).

What are the types of APIs?

There are several broad categories of application programming interface:

• The open API (or Open API) publicly available without restriction,
• The partner API accessible via a license or specific access rights,
• The internal or private API (Private API) designed by a company for its needs.

Why make an API?

An API makes it possible to expose on the web or on a local corporate network a catalog of functionalities from an application, or content from a database or a file system. Purpose: to allow third-party systems to access these features and content. Ultimately, the purpose of an application programming interface is therefore to bring together several software programs.

In recent years, the API has become the reference technology for integrating several business applications. Web and software players are also increasingly using it to provide programmatic access to their offers, and no longer just in the form of traditional graphical interfaces.

API examples

The API allows developers to use a program without having to worry about how it works. APIs can, for example, be used to trigger online advertising campaigns by avoiding having to understand the underlying technical process. This is the case with Google's AdWords API in particular.

APIs are found in many software, in particular in operating systems (Windows, Linux, Mac OS), application servers (Apache), in graphical tools (OpenGL), in SaaS applications (Office 365 , G Suite, Salesforce...), in databases, open data, etc. On the Web, they are typically used to integrate third-party services (eg Google Maps and Facebook) into a site. Another example: airline ticket reservation platforms use it to query the offer available within the systems of the various airlines.

What are API technologies?

There are two main communication protocols on which the APIs are based: Simple Object Access Protocol (SOAP) and Representational State Transfer (REST). The second has now largely imposed itself against the first because it is more flexible. It gave birth to the so-called REST or RESTful APIs).