In building applications, an API simplifies programming by [[Abstraction (software engineering)|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, an API for file [[input/output]] might give the developer a [[Subroutine|emailfunction]] clithat copies a file from one ___location to another without requiring that the developer understand the [[Journaling file system|file system]] operations occurring behind the scenes.<ref name="Clarke4">{{cite web|last1=Clarke|first1=Steven|title=Measuring API Usability|url=http://www.drdobbs.com/windows/measuring-api-usability/184405654|website=Dr. Dobb's|accessdate=29 July 2016|date=2004}}</ref>
[[email client]] might provide a user with a button that performs all the steps for fetching and highlighting new emails, an API for file [[input/output]] might give the developer a [[Subroutine|function]] that copies a file from one ___location to another without requiring that the developer understand the [[Journaling file system|file system]] operations occurring behind the scenes.<ref name="Clarke4">{{cite web|last1=Clarke|first1=Steven|title=Measuring API Usability|url=http://www.drdobbs.com/windows/measuring-api-usability/184405654|website=Dr. Dobb's|accessdate=29 July 2016|date=2004}}</ref>
