My definition: Using a program to emulate a game that will slow it down to frame by frame play but play it back at normal speed. Allowing the game to be played with seemingly super human skill. The goal of which is to find the theoretical minimum completion time of the game without manually editing the game files (hacking). Glitch exploitation is normal as these, although unintended, do exist in the game files naturally. Also they are fairly entertaining.
I'd like to hear people's opinions and stories of TAS's, I do not want this to be a flame war or Assisted vs. Unassisted (natural) runs.
My recent favorite: 21min and some change by inichi on the game Chrono Trigger. Glitch exploitation is an understatement on this one (if you do watch the video remember, if you were some super human you could actually do everything that happens in the video by just knowing how to pull it off).