4.Jimmy Fallon shared this photo of himself as a 15-year-old in 1990 — already testing his comedy chops:
5.Padma Lakshmi posted this too-cute photo of how she looked when she first arrived in the US in 1974:
6.Barbra Streisand shared this behind-the-scenes photo of herself on the set of her film, Up the Sandbox:
7.Heidi Klum posted this photo of herself in the early '90s:
8.Janet Jackson shared this very sweet video clip of herself meeting a fan in the early '00s:
9.Cindy Crawford posted this photo of herself being glam in a barn in the early '00s:
10.Speaking of glam, Debbie Allen shared this gorgeous photo of herself attending her first Oscars in 1991 — wearing Bob Mackie Couture:
11.John Stamos announced he and Nia Vardalos were cohosting a virtual gala to benefit school theaters by sharing these photos of the two of them in high school in the late '70s:
12.Coldplay posted the music video for their 2000 single "Shiver":
13.Salma Hayek shared this sexy photo of herself from the 2000s:
14.Madonna posted these photos of herself from her Like a Virgin era in 1985:
15.And finally, Adele reflected on 21 on its 10th anniversary: