This article is being rewritten at Talk:Speedrun/rewrite.

A speedrun ( ) is a play-through of a computer or video game, created with the intent of completing it as quickly as possible, optionally under certain conditions, mainly for the purposes of entertainment and competition. The term, a compound of the words speed and run (as in “running” through a game, referring to the playing of a game) is only used in the context of games that were not originally or primarily designed with fast completion in mind; one generally does not “speedrun” a racing game (in those cases the game's standard setting for achieving and recording fast times is called a time attack or time trial mode). Although the term “time attack” is used to indicate a playthough of a game's dedicated mode for achieving fast completions, the term “タイムアタック” (“taimuatakku”) is the dominant terminology for both unassisted and tool-assisted speedruns in Japan. There is no commonly used loanword deriving from the term “speedrun”. Speedrunning is often seen as a display of skill and is practiced competitively, as a pastime, in Internet-based communities, on which the resulting movies are released as rendered multimedia versions such as AVI files. Despite a large majority of speedruns being released in a video format, and this largely being the preferred format due to the number of players that can be used to open it, some (game-specific) communities utilize a game's native demo format due to these inherently being much more compact and thus easy to share; even such communities encode major releases in a more ubiquitous format.

In order to attain the highest possible quality of play in a speedrun, the author usually has to look at and think about the game differently than most casual gamers would. Generally, games' physics engines are not flawless and will allow the runner to do unexpected things that could save time. Despite their inherent differences, game engines seem to share a lot of common traits in this context, such as sufficient complexity to warrant a route to be mapped prior to the making of the run; the ability to disjunct the common sequence of events in a game and thus skip entire parts of it, or sequence breaking; and the ability to use programming errors, or glitches, to one's advantage.

Some games have been considered to be ideal specimen for fast completion purposes, and have been supported fanatically by practitioners who have built virtual communities around them, which provide (or have provided) a highly active platform for the discussion and exertion of speedrunning one or more particular games. Speedrunning can provide a medium through which gamers can extend their experience with a game's single-player adventure even if they have already beaten the game.