Unlike other forms of art - tangles can be shaded in more than one way. In fact a picture can be shaded in many different ways which means you could end up with a totally different looking picture depending on what you do. This book not only shows the different ways but gives you the chance to try your hand. The images used aren't all by the same artist which allows the author to give advice on a wider basis. In my experience tangles aren't complete without shading - it really does 'lift' the tangle from being a mere doodle into a work of art.