a clock that maintains the time of day, in contrast to a clock that is used to time the electrical pulses on a circuit.
A computerized clock or timing device that tracks accurate time.
A clock used by a computer that keeps track of time just like a wall clock, or wristwatch. This clock, which often tracks the date as well, continues working when the computer is switched off.
A real-time clock (RTC) is a computer clock (most often in the form of an integrated circuit) that keeps track of the current time. Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are present in most any electronic device which needs to keep accurate time.