Platform

Facebook launched the Facebook Platform on May 24, 2007, providing a framework for software developers to create applications that interact with core Facebook features.^[50][51] A markup language called Facebook markup language was introduced simultaneously; it is used to customize the "look and feel" of applications that developers create. Using the Platform, Facebook launched several new applications,^[50][51] including Gifts, allowing users to send virtual gifts to each other, Marketplace, allowing users to post free classified ads, Events, giving users a method of informing their friends about upcoming events, and Video, letting users share homemade videos with one another.^[52][53]

Applications that have been created on the Platform include chess and Scrabble, which both allow users to play games with their friends.^[54][55] These games are asynchronous, meaning that a user's moves are saved on the website, allowing the next move to be made at any time rather than immediately after the previous move.^[56] Within a few months of launching the Facebook Platform, issues arose regarding "application spam", which involves Facebook applications "spamming" users to request it be installed.^[57] Application spam has been considered one of the possible causes to the drop in visitors to Facebook starting from the beginning of 2008,^{[citation needed]} when its growth had fallen from December 2007 to January 2008, its first drop since its launch in 2004