1. Miley Cyrus is 21, and Bangerz is her fifth No. 1 album.
2. Only one member of One Direction, Louis Tomlinson, is old enough to drink legally in the United States.
3. Lorde wrote "Royals," one of the most popular songs of the year, when she was 16. She's 17 now.
4. "22" is Taylor Swift's 21st single to sell at least 1 million copies. She is 23.
5. Three contestants on American Idol this year were only 8 when Kelly Clarkson won in 2002.
6. Ten years ago, Selena Gomez was singing in a kiddie pool with Barney...
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7. ...and this year she had a top 10 hit with "Come and Get It," a song in which she tells dudes to...come and get it.
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8. Alana Haim was not born until a year after the date printed on her T-shirt on this magazine cover.
9. Justin Timberlake and Beyoncé have been famous singers for 16 years, which is exactly half the time they've both been alive.
10. We now live in a world where people have no idea who NSYNC are.
11. You can say to a kid in high school now that you have MP3s older than them.
12. Blink-182 went out on the final leg of their 20th anniversary tour this year.
13. Outkast's "Hey Ya" is now 10 years old.
14. Oh, and so is Beyoncé's "Crazy in Love"...
15. ...and R. Kelly's "Ignition Remix."
16. ...and The Postal Service's Give Up.
17. The Jonas Brothers broke up this year — seven years, one wedding, and one pregnancy after they first came onto the scene.
18. Daft Punk scored their first multiplatinum hit this year with "Get Lucky," 19 years into their career.
19. Incidentally, that's exactly how old Howard Lawrence, half of the popular dance act Disclosure, is today.
20. Frances Bean Cobain is now 21, and is slowly turning into her mother.
21. Kids who started high school this year have never known a world without "Thong Song."
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22. This is what Miley Cyrus looked like 11 years ago...
23. ...and this, of course, is Miley today.
