Application program interface (API) is a set of routines, protocols, and tools for building software applications. An API specifies how software components should interact and APIs are used when programming graphical user interface (GUI) components. A good API makes it easier to develop a program by providing all the building blocks. A programmer then puts the blocks together.

APIs are a way to create a bridge between multiple applications to allow data to be shared and executed seamlessly. The data sharing can be partial or full – based on the business needs. Since the API does all the data transfer and processing it saves time and cost of updating the system on a regular basis. It also helps in preventing human errors that happen due to updating information on multiple systems.