The document discusses three types of social media: social bookmarks, which allow users to share bookmarks and find groups of information; games and massively multiplayer online role-playing games (MMORPGs), which involve structured play for enjoyment and sometimes education; and social networking sites, which enable building social networks among people with shared interests. Examples provided include Twitter, Reddit, Pinterest, StumbleUpon, Facebook, Myspace, Google+, and Linkin.