how does the function time() tell the current time and even when the computer has been powered off earlier?

Question

how we can work on timer deals with milliseconds (0.001) how we could divide second as we want ?? how we could we deal with the second itself ???

Answer 1

http://computer.howstuffworks.com/question319.htm

In your computer (as well as other gadgets), the battery powers a chip called the Real Time Clock (RTC) chip. The RTC is essentially a quartz watch that runs all the time, whether or not the computer has power. The battery powers this clock. When the computer boots up, part of the process is to query the RTC to get the correct time and date. A little quartz clock like this might run for five to seven years off of a small battery. Then it is time to replace the battery.