What is a calendar?
A calendar is an arrangement of a depiction of time defined by humans.  It is a collection of multiple days that makes up a month with multiple months representing a year of time.  Each day of the week on a calendar is assigned a word to represent the day - Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday.  A calendar is used for planning scheduled events in the future, remembering birthdays, and other important dates like tests in school.  A calendar can also be broken down into seasonal months that represent the months that match the weather during any particular time of the year.