Although we now know that Pope Gregory XIII was also slightly out when he corrected the Julian calendar in 1582, the Gregorian calendar is the method of dating the year adopted by the majority of the world. Accepting that the year is correct - or as near as makes no difference - the last year before the birth of Christ was 1 B.C. (Before Christ), the very next year was 1 A.D. (Anno Domini, meaning "in the year of our Lord"). That is, there was no "Year Zero". Therefore, as year 1 was the first year, it follows that year 2000 was the 2,000th - and the last of the first two thousand years since the birth of Christ. Consequently, the first year of the third millennium is 2001 and NOT 2000. Simple, isn't it?