API stands for Application Programming Interface
A software intermediary that allows two applications to talk to each other
API's are generally dedicated URL's that will return a response - in a format such as JSON - based on the request it recieves. Some are publically available but others require authentication, such as access tokens.
However, an API isn't alwasy based extrernally on a server. It could also be a library such as JQuery which is integrated into an application or web page. You access the methods and make generaly use of the library via your code by using its API.
Benefits of an API
- Speed/Performance - Can pick and choose exactly what data is required and what happends while the clinet is waiting for that request to complete
- Access - From a business or organisation persepctive creating an API allow anyone to access your service or data for whatever uses they wish.
- Security - Both the API and the client are protected as neither have full acess to the other. They communicate with small amounts of data, sharing only what is necessary