When a large number of pixels are needed in a display, it becomes difficult to have enough wires and electrodes to control each pixel and still have a clean display. Instead, the display is "multiplexed". In a multiplexed display, electrodes on one side of the display are grouped and wired together (usually in columns). On the other side, the electrodes are also grouped (typically in rows), with each group getting a voltage sink. By turning on one row and one column, each pixel can be controlled one at a time.