What is an API and how to use one

In some cases, open data is provided through an application programming interface (API), often a web-based method for retrieving, searching or even updating the available information dynamically. APIs provide up-to-date data in a granular and filtered form, removing the need to repeatedly process and update source files.

A common use case for APIs is relatively time-sensitive information, such as procurement calls and contracts which are released every day. In the UK, BusinessLink (http://www.contractsfinder.businesslink.gov.uk/data-feed.aspx) provides a number of data feeds which contain information about procurement notices. Similarly, the USASpending portal provides a set of APIs that can be used to retrieve up-to-date grants information for the US federal government (http://usaspending.gov/data).

[TODO - how to use one]