text: For example, Yahoo's open search API allows developers to integrate Yahoo search into their own software applications. The addition of this API provides search functionality to the developer's application whilst also increasing search traffic for Yahoo's search engine hence benefitting both parties. With respect to Facebook and Twitter, we can see how third parties have enriched these services with their own code. For example, the ability to create an account on an external site/app using your Facebook credentials is made possible using Facebook's open API.
  Many large technology firms, such as Twitter, LinkedIn and Facebook, allow the use of their service by third parties and competitors.
  Open APIs on the Web
  With the rise in prominence of HTML5 and Web 2.0, the modern browsing experience has become interactive and dynamic and this has, in part, been accelerated through the use of open APIs. Some open APIs fetch data from the database behind a website and these are called Web APIs. For example, Google's YouTube API allows developers to integrate YouTube into their applications by providing the capability to search for videos, retrieve standard feeds, and see related content.
  Web APIs are used for exchanging information with a website either by receiving or by sending data. When a web API fetches data from a website, the application makes a HTTP request to the server the site is stored on. The server then sends data back in a format your application expects (if you requested data) or incorporates your changes to the website (if you sent data).