Year zero
Year zero does not exist in the anno Domini system usually used to number years in the Gregorian calendar and in its predecessor, the Julian calendar. In this system, the year is followed by . However, there is a year zero in astronomical year numbering (where it coincides with the Julian year ) and in ISO 8601:2004 (where it coincides with the Gregorian year ) as well as in all Buddhist and Hindu calendars.
500
Year 500 (D) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Patricius and Hypatius (or, less frequently, year 1253 "Ab urbe condita"). The denomination 500 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. The year 500 is considered the beginning of the Middle Ages.