reddit is a social media site founded in 2005. It allows users to submit external links or self-links for discussions. Popular posts are upvoted and end up on the main page, visible for some amount of time until something else overtakes its spot. reddit allows communities to operate subreddits around particular topics and each one is allowed to have a heavily modified and skinned version of a MediaWiki wiki to discuss its rules or create an FAQ. There are over 20,000 subreddits, many of which have a wiki but few of which are particular active as wikis. They are mostly a method of creating documentation unique to each subreddit in a quick and collaborative manner.