What is an API?

The acronym 'API' stands for an extremely importantMaps data templates to build visualisations and tools
part of the world of software development, despitesuch as journey planners or online pedometres, or an
the complete lack of recognition from the widerSMS API for text message marketing campaigns.
world.The most common type of API though has to be
These three letters stand for Applicationthose aimed at web development. Tools for web
Programming Interface and without APIs, a wholedevelopment are often published freely (though
range of integrated digital services would beretaining proprietary rights to the code), with the
unavailable - from posting pictures on socialoverall intent of facilitating the consturction of an
networking sites to sending email via SMS. APIopen architecture for web content and data
implementation is what lets applications, libraries andbetween different applications and online communities.
operating systems understand one another andWeb APIs are typically a defined set of HyperText
interact, turning technology and software fromTransfer Protocol request messages, coupled with a
complex niche devices to broadly accessible,definition of the structure for response messages.
multi-purpose consumer services.Often coded in Extensible Markup Language (XML) or
An API works in a similar way to a user interface;JavaScript Object Notation (JSON) format, they allow
providing an abstract interface for functionalthe combination of multiple services into new online
interaction between different componenets ofapplications commonly known as 'mash-ups'.
different software systems. There are severalThe ability to openly use Web APIs has allowed the
different categories of API, tailored to specific orcreation of a variety of now commonly used web
general uses. The two main categories are:services. Perhaps the best example is the ability to
- General APIs - this is the most extensive form ofembed content from one web page onto another
API, effectively the part of a programming languageweb page through relatively simple HTML code - for
that allows for functional interactivity betweenexample, posting a YouTube video on a web page
different programmes. Examples include the Standardrather than simply posting a link to YouTube. Similarly,
Template Library in C++ or the Java API.an API lies behind the ability to upload a video on
- Specific APIs - these are APIs designed for aFlickr and post it on Facebook or MySpace, as well as
specific problem or purpose. Examples include Googlethe ability to stream live feeds from social media
Maps API, which lets developers access the Googlenetworks such as Twitter on other sites.