Tick group
A named phase of an engine's per-frame update that controls when a piece of code runs relative to physics.
Order within a frame is not arbitrary. Move a character before or after collision resolution and you get different behaviour, and if you want to read a bone's position after the simulation, your code has to run after physics, not before. Tick groups are the engine's way of letting you choose where in the game loop something lands.
Unreal Engine names its phases explicitly: PrePhysics, DuringPhysics, PostPhysics, PostUpdateWork. Unity splits the same idea across Update, FixedUpdate and LateUpdate. Guessing the group wrong is a classic source of one-frame-late jitter — a bug that is genuinely maddening to track down precisely because everything "almost" looks right.