Everyday Life
Why Are There Seven Days in a Week?
No natural cycle sets the week. Seven days came from Babylonian, Jewish and Roman traditions and seven visible planets, and survived French and Soviet reforms.
Everyday Life
The reasons behind ordinary things, from calendars and clocks to household habits and the customs we follow without thinking.
Everyday Life
Why Do We Have Daylight Saving Time?
Daylight saving time moves clocks ahead one hour to shift daylight to the evening. Learn where it began, how U.S. law works and whether it saves energy.
Everyday Life
Why Do We Have Leap Years?
Leap years add February 29 because the seasons repeat about every 365.2422 days. See how the four-year rule and the century exception keep the calendar right.