A 13-hour clock has been released as a "tongue-in-cheek" protest about the gender pay gap in New Zealand. It's paired with a diary with an extra month in the year, as part of a publicity campaign ...

The brain has a master clock that is set by exposure to sunlight and darkness. This circadian rhythm is a roughly 24-hour cycle that determines when we become sleepy and when we’re more alert.

Military time, also known as the 24-hour clock, is a system the military uses to eliminate confusion between morning and afternoon hours, since the armed forces are in operation around the clock.

An analogue clock, a clock with hands, shows the numbers 1 through to 12. It is a 12-hour clock. The first 12 hours of the day, from midnight to midday, are called am. The next 12 hours ...