Question

what is tiling with reference to background lmages

Answer 1

You will often need to use reference photos to guide your modeling. Among the many things you can do with photos and other images in Blender, it is possible to use them just as guides in the 3D view, such that they do not appear in the final render. Furthermore these images will only be visible when the view is orthographic and exactly aligned to one of the X, Y or Z axes (or the camera view). This way, they can be used as a precise reference for positioning elements of the model.