A device used to mark time by means of regularly recurring ticks or flashes at adjustable intervals. They are commonly used by musicians to establish a consistent tempo that can be followed when performing musical parts. Early designs were mechanical, using a swinging pendulum that generated a ‘click’ sound at the bottom of the motion. Many musicians still prefer these due to the visual cues supplied by the swinging arm. A good one has a very natural motion that gives the player a nice ‘feel’ for the tempo, which makes it easy to anticipate or lag behind the beat a little bit as desired. Many modern designs are electronic and range from very simple little ticking boxes to elaborate visual displays. Some are even capable of counting out loud, “One, Two, Three, Four,” etc.