This short book, which includes patterns and pictures, is all about crocheting rugs using rags, not yarn. Crocheting with yarn is very well-known, but I have never heard of crocheting with rags. It sounds like a good way to get rid of excess fabric.
It talks about how to attach the 1-inch wide strips of fabric together, in order to make longer strips. Before you even start cutting your fabric strips, it might be good to estimate just how much will be needed; the book covers it. Another important point to remember is making sure that the rug will stay flat when it goes on the floor.
The book shows pictures of different kinds of rugs. There is a basic round rug, a rectangular rug (where it's OK to change colors every few rows), the well-known oval rug, a heart-shaped rug, a slice rag rug (that looks like a round rug that has been cut in half) and a harvest rug. Instructions are included with each picture, instructions that are written in Crochet, not in English.
Those who know how to use a crochet needle could do a lot worse than buy this book. The patterns and instructions seem like they are easy-to-follow. It is very much worth considering.