In tapestry weaving, the relationship between warp and weft is an important one. How to reach a happy consensus between these two elements of your piece is not immediately obvious.
These questions might sound familiar:
What warp should I use? How do I even decide with all those numbers?
Why is my warp showing?
Why does this weft yarn look so bad woven when it is so pretty in the skein?
Why is my fabric so loose?
The warp has a big job. Warp is the ground of your piece. It is the tightly-held strings upon which your image is built. The warp is completely covered in traditional tapestry weaving, yet it is the necessary core of the structure.