I was first introduced to restorative yoga several years ago by Judith Hanson Lasater and have studied it a great deal since, both with Judith, and Anna Ashby.
Restorative Yoga is designed for deep relaxation by using passive poses and supporting the body with a variety of props. This allows the nervous system to settle and encourage deep relaxation, bringing a sense of peace and calm throughout your body and mind, helping you feel stronger, both emotionally and physically.
I have found it to be incredibly powerful. I love how when I teach my students they almost float from the class with a smile on their faces and sense of being more grounded than when they first walked in.