The dimple board reduces the risk of water or moisture passing through the walls. Dimple Boards have a variety in them, and they are constructed from many materials. For example, some simple boards will be made from polypropylene or a polyethylene sheet; some will have molded dimples or knobs. Each structure is different and depends upon the thickness implemented into it.
The thing about Dimple Boards is that it has to be installed correctly on the concrete wall to help prevent water flowage from inside your walls. If it is not installed correctly, water will flow directly from your walls.