An hour is a period of sixty minutes.

People say that something takes or lasts hours to emphasize that it takes or lasts a very long time, or what seems like a very long time.

A clock that strikes the hour strikes when it is exactly one o'clock, two o'clock, and so on.

You can refer to a particular time or moment as a particular hour .

If you refer, for example, to someone's hour of need or hour of happiness, you are referring to the time in their life when they are or were experiencing that condition or feeling.

You can refer to the period of time during which something happens or operates each day as the hours during which it happens or operates.

If you refer to the hours involved in a job, you are talking about how long you spend each week doing it and when you do it.

If you do something after hours, you do it outside normal business hours or the time when you are usually at work.

If you say that something happens at all hours of the day or night, you disapprove of it happening at the time that it does or as often as it does.

If something happens in the early hours or in the small hours, it happens in the early morning after midnight.

If you say that someone does something hour after hour, you are emphasizing that they do it continually for a long time.

If something happens on the hour, it happens every hour at, for example, nine o'clock, ten o'clock, and so on, and not at any number of minutes past an hour.

If you want to state the time exactly, you can give a number of minutes followed by before the hour or past the hour .

Something that happens out of hours happens at a time that is not during the usual hours of business or work.