Calendar

==Formats==
{{Unreferenced section|date=April 2023}}
[[File:Petaluma and Santa Rosa Railroad Co. Calendar.jpg|thumb|A calendar from the [[Petaluma and Santa Rosa Railroad]]]]

The term ''calendar'' applies not only to a given scheme of timekeeping but also to a specific record or device displaying such a scheme, for example, an [[appointment book]] in the form of a pocket calendar (or [[personal organizer]]), desktop calendar, a [[wall calendar]], etc.

In a paper calendar, one or two sheets can show a single day, a week, a month, or a year. If a sheet is for a single day, it easily shows the date and the weekday. If a sheet is for multiple days it shows a conversion table to convert from weekday to date and back. With a special pointing device, or by crossing out past days, it may indicate the current date and weekday. This is the most common usage of the word.

In the US Sunday is considered the first day of the week and so appears on the far left and Saturday the last day of the week appearing on the far right. In Britain, the weekend may appear at the end of the week so the first day is Monday and the last day is Sunday.{{cn|date=April 2023}} The US calendar display is also used in Britain.

It is common to display the Gregorian calendar in separate monthly grids of seven columns (from Monday to Sunday, or Sunday to Saturday depending on which day is considered to start the week&nbsp;– this varies according to country){{cn|date=April 2023}} and five to six rows (or rarely, four rows when the month of February contains 28 days in [[common year]]s beginning on the first day of the week), with the day of the month numbered in each cell, beginning with 1.   The sixth row is sometimes eliminated by marking 23/30 and 24/31 together as necessary.

When working with weeks rather than months, a continuous format is sometimes more convenient, where no blank cells are inserted to ensure that the first day of a new month begins on a fresh row.