Understanding UVs and texture coordinates
While you are modeling, you are altering the coordinates of the vertices of a model. Thus, you are working with spatial coordinates. To apply a texture over your model, you need to work in a different kind of coordinate system that is called texture coordinates or UVs. Let’s see how these two terms relate to each other.
The spatial coordinate system is often described with the XYZ acronym since we often use X, Y, and Z axes to define the position of 3D objects. Similarly, UV is another acronym but it is used in the texturing workflow; the letters U and V were picked to describe the texture coordinate system. So, UV doesn’t really stand for ultraviolet.
The process that maps UV coordinates to XYZ coordinates is called UV unwrapping. Via this method, you tell Blender how a graphic file is mapped to XYZ coordinates. If unwrapping sounds counterintuitive, you could try to reverse the process in your mind. What kind of texture...