Object space
A model's own coordinate system, where its vertices live before anyone has decided where in the world it belongs.
When an artist builds a chair in Blender, the origin ends up wherever they happened to put it — the middle of the seat, between the legs, or in a corner by accident. That point ships with the asset: every vertex in the file is stored relative to it, and it is what the model rotates and scales around. A badly placed pivot shows up immediately, as a door that spins around its centre instead of its hinges.
The model matrix carries the vertices on into world space, and the chain continues through view space and clip space. Normal maps can be baked in object space too; they are cheaper than the tangent-space kind, but can't be reused on another mesh and don't follow along when a skeleton bends the surface.