A
timer is a specialized type of
clock. A timer can be used to control the sequence of an event or process. Whereas a
stopwatch counts upwards from zero for measuring elapsed time, a
timer counts down from a specified time interval, like an
hourglass. Timers can be
mechanical,
electromechanical,
electronic (quartz), or even
software as all modern
computers include digital timers of one kind or another. When the set period expires some timers simply indicate so (e.g., by an audible signal), while others operate electrical switches, such as a
time switch, which cuts electrical power.
