1.Britney Spears posted this iconic photo of herself from 2003.
2.In honor of her friend Debi Mazar's birthday, Madonna shared this photo of the two of them back in the '80s.
3.Paul McCartney was in a summer mood in his #TBT and posted this photo of himself vacationing in Antigua back in the day.
4.Jamie Lee Curtis posted a pic of herself with her daughter back in 1987 — it also demonstrated the original way you had to take a selfie.
5.Iman shared this oh-so-'80s photo.
6.Gina Rodriguez posted this now and then photo of herself with her mom and dad.
7.Michelle Trachtenberg shared this photo of when she was a child model.
8.Mayim Bialik took it back to her Blossom days.
9.Mandy Moore posted this photo of herself getting ~glammed up~ as a kid.
10.Angela Kinsey shared this behind-the-scenes photo of herself on the set of the office with co-star Jenna Fischer — while John Krasinski chilled in the background.
11.Naomi Campbell posted this iconic photo of herself — with fellow supermodels Stephanie Seymour, Cindy Crawford, Tatjana Patitz, and Christy Turlington — in honor of her late friend, photographer Herb Ritts.
12.And finally, Chelsea Clinton shared this photo of herself with her dad, Bill Clinton (of course), in honor of his milestone birthday.