The division of the year into months, weeks, and days and the method of ordering the years (past, present, and future): LVirginia checked the calendar in her kitchen to see what day of the week her daughter's birthday was on in June.

From year one, an assumed date of the birth of Jesus, dates are calculated backwards (B.C., "before Christ" or B.C.E., "before common era") and forwards (A.D., Latin anno Domini, "in the year of the Lord", or C.E. "common era").