Time is something that most of us take for granted. Have you ever thought about why, for example, there are 12 months in a year? Why are there 30 days in September? Why are there time zones and what's with daylight-saving time? Why are there 86,400 seconds in a day?

In this edition of HowStuffWorks, we'll help to clarify the subject of time. In the same way that many of the traditions surrounding Christmas and Halloween have totally unexpected origins, so do the traditions surrounding clocks and calendars!