This occurs when the PC (Playable Character) uses a wooden plate to clip through the collision meshes of objects or buildings. This works by holding a plate at head level and running or sprinting into it causing the game to reset collision meshes of the plate allowing the player to "walk through objects".
There is some patches in place to prevent this glitch to happen. At Dragonsreach the quest door has dressers blocking it so when you glitch through you respawn at the main entrance.
- Getting to merchant chests
- Getting through locked or inaccessible areas
- Speed Running with this glitch