A shower valve is a device that controls the flow of water in a tub or shower. It is often used as an alternative to a showerhead. A shower valve is typically found on the end of a tub or on the wall of a shower. The valve is opened and closed with a handle that controls a lever. When the lever is turned, it opens or closes the valve. Shower valves can be found in a variety of shapes and sizes, depending on the needs of the user.