what's on the calendar?
For other uses, see Calendar (disambiguation). For the Gregorian calendar for this year, see Leap year starting on Friday. A calendar is a system of organizing days for social, religious, commercial or administrative purposes. This is done by giving names to periods of time, typically days, weeks, months, and years. A date is the designation of a single, specific day within such a system. A calendar is also a physical record (often paper) of such a system.