what is an rtc

A Real-Time Clock (RTC) is an electronic device that measures the passage of time. It is an integrated circuit that contains a timer that supplies the time of day (and often, the date) . RTCs are present in almost any electronic device which needs to keep accurate time of day, such as personal computers, servers, embedded systems, and other electronic devices. RTCs often have an alternate source of power, so they can continue to keep time while the primary source of power is off or unavailable. This alternate source of power is normally a lithium battery in older systems, but some newer systems use a supercapacitor because they are rechargeable and can be soldered. RTCs are not to be confused with real-time computing, which shares its three-letter acronym but does not directly relate to time of day.