Superficial understanding of UNITY canvas

Canvas: When the canvas is a screen-space overlay, this is easy to understand, and the canvas can be controlled such as resolution, level, etc.
But when the canvas is world-space, this is not strictly a canvas. The canvas of screen space or camera space is first drawn to a map, and then the map is posted to the viewport, while the world space canvas is not In this way, because the elements in the world space canvas need to have an occlusion relationship with the objects in the world space, therefore, in fact, each UI in the world space canvas is a world space object, which is no different from ordinary 3D objects. The world space canvas This concept is almost useless, one role is to tell U3D to convert our UI to world space objects.
---The most important point of the world space canvas: its UI is a world space object, just like a normal 3D object