When traveling, it is nice to be able to take an alarm clock with you. Sure, the hotel will probably have one, but they are often difficult to set. And the “wake up service” they provide can have its problems – which you won’t know until after you aren’t woken up in time for your [...]

Digital atomic clocks are extremely accurate in timekeeping. They automatically synchronize themselves, usually every night, and have an accuracy of better than one second off ever 80 million years. Because of this high level of accuracy, they are used for scientific purposes as well as convenient for the individual.
The Very Basics
All clocks keep track of [...]