This article is about the year 2000. For other uses of 2000, see 2000 (number) or 2000 (breakdancing move).

2000 (MM) was a leap year starting on Saturday of the Gregorian calendar. In the Chinese Calendar it is the Year of the Dragon and in the western astrological calendar it is the year of Leo, the Lion. Popular culture also holds the year 2000 as the first year of the twenty first century and the third millennium. By strict interpretation of the Gregorian Calendar, however, this distinction falls to the year 2001. This is because the first century began with the year 1 (there was no year zero), the first century (or first 100 years AD) was from January 1, in the year one (AD 1) through December 31, in the year one-hundred (AD 100). The second century began on January 1, in the year one-hundred and one (101 AD). (The selection of AD 1 may be up to seven years from Jesus' birth, and January 1 is a historical choice for New Year's Day. 2000-01-01 is the day all the digits "rolled over".)

The year 2000 was also marked as:

• The International Year for a Culture of Peace.
• The World Mathematical Year.