The year 2000 is the last year of the 20th Century. The year 2001 is the first year of the 21st Century.
Without going into the history of our calender, the basic reason for this is that our calender has no year 0. It goes from 1 BC to AD 1. The first year of the first century was 1 AD. Each century after that started on the 1 year, 101, 201, 301, etc... The 1000th year ended at the end of the year AD 1000. The 2000th year ends at the end of the year 2000. Technically, being born in 1970 means that I am a child of the 60's and the 1998 Winter Olympics are not the last Olympics of the 20th Century, the 2000 Summer Olympics will be. So, if you go celebrate the end of the millenium on December 31st, 1999, then you will be a year early. That's not too bad out of a thousand years, but wrong nonetheless.
Bolie IV