To understand meshes, we should start at the bottom. Vertexes define a polygon. The polygons make up your object. A mesh is a collection of the vertexes. Another name for mesh is model. You create your model outside of Unity with a product like Blender.
Shaders are code that describe how light interacts with your object. For example, your shader might project an image onto your object and show how shadows are formed.
Unity handles some of the movement details that I recall implementing in my last game by hand. Objects just don't jump around from one position to the next. The move slowly through each frame. This move is called tweening.
There are four coodinate systems to describe an object or point posisition in Unity:
- Screen space
- Viewport space
- World space
- Local space