When did the 21st century start?

My parents always taught me that the 21st century started on January 1, 2000, but Wikipedia says it started on January 1, 2001 and that it is distinct from the century known as the 2000s which began on January 1, 2000 and will end on December 31, 2099. What is the difference? Are there 2 different centuries... show more My parents always taught me that the 21st century started on January 1, 2000, but Wikipedia says it started on January 1, 2001 and that it is distinct from the century known as the 2000s which began on January 1, 2000 and will end on December 31, 2099.

What is the difference?
Are there 2 different centuries ?

Lol, I dont get it, I was searching for the difference but couldn’t find it and I am confused about when the 21st century started.
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