Hi LiZebin
There is a common mistake here..First is millenium which correctly means a period of a thousand years while the famous generation is call Millenial/s and they are not born in the year 2000 (post millenials or Generation Z) but are born between 1981 and 1996, so..
Millennium literally means a period of one thousand years while the generation born between 1981 and 1996 are known as the Millennials. They grew up with the internet, playing video games, using mobile phones and so on. So they have quite different interests from their parents.