Simplify the following text for a Grade 12 native English-speaking person.
Original: The Sydney 2000 Summer Olympic Games or the Millennium Games\/Games of the New Millennium , officially known as the Games of the XXVII Olympiad , were an international multi-sport event which was celebrated between 16 September and 1 October 2000 in Sydney , New South Wales , Australia .
Simplified: The 2000 Summer Olympics , officially known as the Games of the XXVII Olympiad , were celebrated in Sydney , Australia from September 15 , 2000 , until October 1 , 2000 .