How is fabric formed?

First you take some sort of thread, whether it be wool, silk, cotton, or nylon (acrylic), then you weave it.

In weaving, you stretch a bunch of threads up and down, (they are called warp threads) Then you take another piece of thread and weave it under and over the warp threads and you end up with fabric.

You can make a small piece of fabric yourself. See the link I have provided.