Application Program Interfaces are, broadly speaking, tools for building software applications. An operating system API might help you build applications with a consistent interface, but Web APIs are mostly about giving you access to data. Even Web APIs aren’t a new idea. Google’s search API has been available via SOAP since 2002, and there’s definitely older services than that. However, the recent growth in Web API availability has been fuelled by two recent developments. The first, which I’ve already mentioned, was a philosophical change in the way that data is handled. The second was the introduction of AJAX. Again, not a new idea, or even a new technology, but sometimes it’s all about timing.

Website: http://www.thinkvitamin.com/features/ajax/go-forth-and-api