In building applications, an API (application programming interface)

simplifies programming by abstracting the underlying implementation and only exposing objects or actions the developer needs.

While a graphical interface for an email client might provide a user with a button that performs all the steps for fetching and highlighting new emails, a

n API for file input/output might give the developer a function that copies a file from one location

to another without requiring that the developer understand the file system operations occurring behind the scenes.