Minecraft wiki entry for Mechanics, associated text: Crawling: Players can switch to a prone (face-down) 0.6-block-high position to fit into 1-block-high spaces.
Flying: In Creative and Spectator modes, players can fly through a world.
Gliding: Players wearing an elytra can glide through the world, optionally using firework rockets to gain speed and/or height.
Jumping: Players jump onto blocks above their current foot level.
Lying: Players (and a few mobs) adopt a special 0.2-block-high position (prone, face-up) when sleeping.
Sitting: Players and many other mobs adopt a sitting position when riding an entity (boat, minecart) or mob.
Sneaking: Players can sneak to hide their names from other players, reduce their hitbox to fit into smaller places, and reduce the range that mobs can detect them at.
Sprinting: Players can shift from "walking" to a faster "running" pace at the expense of hunger.
Swimming: Players can travel on or under water without falling to the bottom, and can travel faster if swimming is combined with sprinting.
Walking: Players can travel any direction on a level surface.