Despite the best efforts of diligent designers and concerned coders, sometimes things don't always go as planned in video games.  These unexpected little faults in the game's system are known as glitches or bugs.  The term glitch actually comes from the German "glitschig," which means "slippery."  And trying to pin down the cause of a glitch can prove slippery indeed for most game designers.  

Glitches can occur in computers and any other form of electronics.  When they happen in video games, glitches cause behavior not originally intended by the programmers.  Game companies employ testers to repeatedly play through the game to check for potential glitches.  When a mistake is found, a report is sent back to the programmers and the appropriate steps are taken to correct the problem.  Yet even the best efforts of video game designers, programmers, and testers can't catch everything.  Glitches always seem to slip through the cracks.  

Common video game glitches include incorrectly displayed graphics, improper collision detection between characters and the environment, and bizarre sound issues.  Some glitches can be humorous, while others can be completely destructive, causing the game to malfunction and freeze up.  

Some gamers actively try to discover glitches in their video games, hoping to exploit the errors to find success or achieve something the programmers never imagined.  The process is known as "glitching" and has become very popular among avid gamers looking to bring new life to their old video games.