The word glitch is a very broad term that can be used to described many different types of strange occurrences in video games.
Types of glitches
Below are common ways in which glitches are categorized.
A clipping glitch occurs when a player or an object within a game environment passed through a texture or level geometry. Clipping is often used to gain access to previously inaccessible parts of a level.
“Outside of the Map”
“Outside of the map” glitches are performed when a game player leaves the normal bounds of a game environment through some means. This is often referred to as “Out of Bounds” (OoB), as well.
When a glitch is performed through a game's menu system or another similar game interface then they have done an Interface glitch.
Jumping glitches occur when a player uses their avatar to move in such a way that defies the game designer's intentions. Jumping is typically used to reach locations within or outside of a level that are normally not intended to be reached.
These glitches most commonly occur independently of the player, but in some cases they can be induced. When a loading glitch occurs the player will often see things such as flickering/missing/incorrect textures, strange coloration, missing or disappearing geometry, a poor framerate, and others.
Physics-Based glitches occur when a player utilizes a game's physics engine in some fashion to perform an action not intended to take place. Launching and pressure launching are common glitch types that are physics-related.
A sequence break occurs when a player is able to bypass a game's narrative or physical structure to reach a location that was not meant to be accessible until later. The speedrunning community is the group most commonly associated with sequence breaking.
A game breaking glitch is one that alters the game in a way that makes the player unable to proceed in the narrative. Examples of these include scripted sequences not triggering or game crashes when story-driven events occur.
Though glitchers often work alone when looking for and discovering glitches, there are many different glitch-focused communities that serve as a home for glitch fetishists. Glitch-related websites exist for single games or series, clans that focus solely on glitching, sites that deal with glitches in general, and sites that desire to archive glitches as they are discovered.
The main source of controversy surrounding glitching is its presence and prevalence in online multiplayer games. Players who utilize glitches in ranked matches, in particular, are almost universally despised by players who do not use them, because players who act in such a manner are technically cheating. As a result of glitchers' actions in multiplayer games, game developers often release patches and game updates to address the discovery of glitches in their games.