Facebook is a social networking website, founded in 2004. This is a list of features that can be found on the Facebook website, as well as technology features on the website.

On April 5, 2008, Facebook pre-released Facebook Chat. As of April 23, 2008, Facebook Chat was released to the entire Facebook user base. Users may chat with their Facebook friends on a one-to-one basis, or a user may chat with multiple friends simultaneously through the groups feature. Instant messaging clients that currently support Facebook Chat include Yahoo! Messenger version 11.0 and later, Skype version 5 or later, AOL Instant Messenger, eBuddy, Flock, Miranda IM, Trillian, Empathy, Pidgin, Adium, Nimbuzz, FIM (Windows Mobile / Windows Phone 7), Palringo (Windows Mobile), Meebo, Tokbox as well as QIP Infium with a Firefox plugin. Windows Live Messenger 2011 (Wave 4) can connect to Facebook as well. Facebook Chat can also be run on the desktop using Gabtastik, a dedicated web chat browser. Facebook Chat can also be run on the iPhone using Facebook Chat for iPhone app. Facebook also released the official app for iPad. Facebook chat is also available to use for Blackberry users via the Blackberry Facebook app. On May 13, 2008, a Facebook developer announced that they are working on XMPP support, allowing hundreds of instant messaging clients to interoperate with the service; this functionality became operational on February 10, 2010. In November 2010, Facebook released a major upgrade of its Messages feature, which merged Chat and E-mail into the Inbox. However, users can still only chat with friends and group members.

A like button, like option or recommend button is a feature in communication software such as social networking services, Internet forums, news websites and blogs where the user can express that he/she likes, enjoys or supports certain content. Internet services that feature like buttons usually display the quantity of users who liked each content, and may show a full or partial list of them. This is a quantitative alternative to other methods of expressing reaction to content, like writing a reply text.

Some websites also include a dislike button, so the user can either vote in favour, against or neutrally. Other websites include more complex Web content voting systems, for example five stars.

Like buttons as used by social networks on websites other than their own are often used as web bugs to track user activities for targeted advertising such as behavioral targeting combined with personally identifiable information (PII) and may be considered a breach of browser security and internet safety privacy concerns.