API is an abbreviation for Application Programming Interface. According to Wikipedia:
"API is a set of routines, protocols, and tools for building software applications."
In our case, we will use the web API to connect to different websites and download the data. Here are some examples of API and XML technologies that can be used with R:
Most of the news agencies allow users to download data related to articles, news, and so on
Many social networking websites such as Twitter and Facebook allow their users to download data related to status updates, friend lists, photos, and links
Google API allows its users to download various kinds of data, such as data related to distances, location, books, authors, web searches, and so on
Note that many websites charge for their services and creating a login is necessary. Many websites allow a certain number of calls to the API service free of charge. Readers new to API should also note that some websites have a separate...