Glide

In Doom speedrunning, a Glide is a movement through a space which was not supposed to be passable through by the level design, but still can be passed due to a glitch in game engine. Glide is possible when a space is 32 units wide, and player's position relative to the space has no fractional component, and is facing in the direction of one of the axes. Various methods exist for executing glides.

Types
A guided, or "right angle" glide is one in which there are two perpendicular walls, with 32 units of space between them (e.g. doom2 map16). In order for the glide to succeed, the player must simply align their angle with the space and use forward mouse sensitivity to push themselves through.

A flat faced glide is one in which both edges of the glide are flat, and the player must align himself both angularly, and positionally precisely in the middle of the gap (e.g. doom2 map02). This variety is rarely done in non tool-assisted speedruns due to the fact that such glides often have monsters in close proximity which can ruin the player's attempts at positioning.