A Web API, or Application Programming Interface, is a framework that allows developers to create HTTP-based services that can be accessed over the web using the HTTP protocol. It is a set of functions that allows programmers to acquire specific features or data of an application. Web APIs can be developed using different technologies such as Java, .NET, and others. There are two types of Web APIs: client-side and server-side. Client-side Web APIs are programmatic interfaces that extend functionality within a web browser or other HTTP client, while server-side Web APIs are interfaces for the outside world to interact with the business logic.
Web APIs can be used to extend the functionality of a web browser or a web server. For example, the Geolocation API can return the coordinates of where the browser is located. Third-party APIs, such as the YouTube API, Twitter API, and Facebook API, are not built into the browser and require downloading the code from the web.
Web APIs are very useful in implementing RESTful web services using .NET framework. ASP.NET Web API is an extensible framework for building HTTP-based services that can be accessed in different applications on different platforms such as web, windows, mobile, etc. It works more or less the same way as an ASP.NET MVC web application, except that it sends data as a response instead of an HTML view.
