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.
2000s (decade)
In the English-speaking world, a name for the decade was never universally accepted in the same manner as for decades such as the '80s, the '90s, etc. Orthographically, the decade can be written as the "2000s" or the 00s". Common suggestions for referring to this decade: "2000s", "Two-thousands", "Twenty Hundreds", "Twenty-ohs", "00s" (pronounced "Ohs", "Oh Ohs", "Double Ohs" or "Ooze", "Zeros", "Double Zeros"), "the Aughts", "the Noughties", "the Aughties", "the Oughties". Other suggestions from 45 countries suggest the "double nothings", "zilches", "oh-zone", "oh-something". When the "20–" is dropped, the individual years within the decade are usually referred to as starting with an "oh", such as "oh-seven" to refer to the year 2007. During the decade of the 2000s, it was more common to hear years referred to starting with "two-thousand (and)" rather than "twenty-oh". Starting around the middle of the 2010s, it is becoming more common to refer to the individual years of the decade as "twenty-oh-seven" or "twenty-oh-eight" than it had been during the 2000s, although the "two thousand (and)" pattern is still dominant.