The 2000s (pronounced “two thousands”) refers to the decade from January 1, 2000, to December 31, 2009. This was the first decade of the 21st century and the third millennium, a period when the world became dramatically more connected through technology.

The 2000s saw the rise of social media, with platforms like Facebook and YouTube transforming how people communicated and shared information. Smartphones began appearing late in the decade, putting cameras, music players, and the internet in people's pockets. These changes meant that for the first time in history, a kid in Kansas could instantly see videos made by someone in Kenya, or share photos with friends across the country in seconds.

The decade opened with both excitement about the new millennium and anxiety about the “Y2K bug,” a computer problem that turned out to be manageable. Major events included the September 11 attacks in 2001, which changed air travel and international relations, and Hurricane Katrina in 2005, which devastated New Orleans. The decade ended with a serious financial crisis that affected families and businesses worldwide.

In popular culture, the 2000s brought us movies like The Lord of the Rings trilogy, the final Harry Potter books, and the beginning of the Marvel Cinematic Universe with Iron Man in 2008. Kids played with iPods and Nintendo Wii consoles.

People sometimes call this decade “the aughts” or “the noughties,” though no single nickname ever became standard.