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You are probably familiar with the saying, that Timing is Everything. The gist of the term is that in order to accomplish
something, efforts and actions must be done at just the right time. For example, actuating an air bag in a car 1/2 second early or late can have disastrous consequences.
Timers are the heart of most processes. The timer or clock controls when events are permitted to happen. The faster the operation,
the more precise the time packets need to be. Splitting time into seconds or even milliseconds (thousandths of a second) is of little value if processes (such as the ) are operating in millionths of
a second, for example the switching of memory instructions in your computer.
 Dial type clocks have the familiar round face with 12 hours being displayed. These are generally
electric (synchronous motor) powered or battery powered with quartz crystal control. There are even models that use a radio signal to check and synchronize with the US. Atomic Clock. In the U.S.,
mechanical spring wound or weight powered clocks are more commonly used for their decorative or collectable value then their precision. Of course the down side is the need for
dependable electric power supply or inexpensive batteries.
Timers are a broad category of time measuring instruments. They are used
to measure time between events. On the rather crude side is the  “egg timer” which is a special sand glass.  It is actuated by
turning it over (start event when the egg starts cooking) and stops when the last sand runs out which visually indicates the stop event (remove the egg). The start/stop event may be pushing
the stem of a stop watch for elapsed time, mechanical switches attached to the timer clock to start and stop electrical devices, or electronic signals to and from programmed timers.
A rather special timer is a chronometer or chronograph. The term is
commonly used by watch manufacturers as a feature of their product in place of the term “stop watch”. However it is more accurately applied to a timer with
extremely high accuracy and precise start and stop event actuation. They are utilized for “official” lap timing at sporting events as well as ballistics. A
popular use is for a shooting enthusiasts. A moderately accurate unit can generally be purchased for under $150 to measure speeds up to 7000 feet per second with 0.5% accuracy.
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