API (Application Programming Interface) refers to a particular set of protocols, standards, and certain tools that a programmer can use to amalgamate multiple applications. Not only do APIs allow you to link to another application or platform, they also allow apps to communicate with one another. APIs not only make development easier, but they also improve the overall user experience, making your application more popular and allowing users to access multiple applications. Specialized APIs, in the modern era, are being used to improve advanced applications.
APIs come in a variety of orientations. They differ depending on the programming language used – procedural, object-oriented, etc. – for applications such as Google Maps, Facebook, Twitter, and LinkedIn), for a web-based system or perhaps websites like Flipkart or eBay, for operating systems such as Debian, Linux, and Microsoft Windows, databases, various hardware components and for a software library. There are three basic policies for publishing APIs: private (for internal usage), partner (for commercial partnerships), and public (for the general public).