Glitch

A glitch is an unintended loophole, occurrence, shortcut, etc. in a game. It can be caused by any number of things, from buggy gameplay, to abuseable physics, to manipulation of the way the game handles things. Some glitches simply do weird things and possibly even break the game, and in some particularly bad cases, corrupt save files. Others can be beneficial, making the game easier, or even much faster to play through-- which is why they are often used in speedruns, particularly tool-assisted ones.

What is NOT a glitch

 * Short circuiting a computer(However, similar practices like Cartridge tilting can produce glitches)
 * Putting a gameboy in a microwave and giggling
 * Cheat Codes
 * Little odds and ends that the designers meant to put in.
 * Hints
 * Holding a Magnet up to the screen
 * Corrupted games
 * Intentionally-crappy games