Armies started using the 24-hour method of timekeeping as standard military time because, much like police, fire, and medical departments, every branch of the armed services is in continuous operation ...

It’s a marvel any of us ever learns to tell time. One “day” of 24 hours divided at noon into two 12-hour chunks — why 24 and 12? And each hour consists of 60 minutes with 60 seconds to a minute — why ...

Different time formats might seem baffling at first, but the 12-hour and 24-hour clocks each tell fascinating stories about how we've measured our days throughout history. The familiar 12-hour system, ...