Holds come in different colours, those of the same colour often being used to denote a route, allowing routes of different difficulty levels to be overlaid on one another. Coloured tape placed under climbing holds is another way that is often used to mark different climbing routes. In attempting a given route, a climber is only allowed to use grips of the designated colour as handholds but is usually allowed to use both handholds and footholds of the designated colour and surface structures and textures of the "rockface" as footholds.