Application Programming Interface

What’s an API?

If you’re not a programmer (and maybe even if you are), the first question you may be asking is “What is an API?”. API stands for Application Programming Interface, but that probably doesn’t help you much :-)

In the modern web-based programming world, software often needs to talk to other software. This allows people to take advantage of features in your software when they create their own software.

• If you want to allow other software to talk to your software, you program it with an API. This API defines the ways in which other programs can talk to your software. The API defines the set of function calls that can be made to the software by external programs to either tell it to do something or get some information from the software. Not every piece of software has an API, however, because it takes extra programming work to support an API.

• Software programs with APIs are often considered “backend” or “middle-ware” software, because they frequently don’t have their own user-interface (users don’t “talk” to them, only other programs do). In such case, users interact with other programs that then talk to the software that has the API.

• But this isn’t a hard-and-fast rule: some software with its own user-interface may also have an API. In such cases the API is often used to by scripts that mimic the behavior of a bunch of user actions (these scripts are often called macros). If you’ve used a spreadsheet program, you may be familiar with its language for creating macros. That’s an API for the spreadsheet software, although in this case the API isn’t used by other programs, but directly by users themselves.