This is the picture that has everyone talking - the woman now known as Caitlyn debuting on the cover of Vanity Fair.
Her former self is Bruce Jenner, an Olympic athlete who said he has been living a lie everyday, because he was meant to be a girl.
Sex expert, Dr. Laura Berman explains the complexities of being transgender.
"It's not an illness, not a malady, not a brain dysfunction," she said. "But where is your gender housed? Your sense of your gender as being a female. Could you identify that inside of you.
"It's hormonal, it's psychological it's neurological. No one can tell us where our gender is, but we know what our gender is."
A researcher at UCLA estimates there are 700,000 transgender adults in the United States who often severely struggle to live in a body that conflicts with their minds.
"The incidents of suicide, depression, drug use and abuse - especially as transgender kids become teens and the sense of isolation and confusion is really astronomical," Berman said.
That's why for Caitlyn to be so public, is a real game changer, Berman said.
"I'm so happy that Bruce Jenner is coming out and claiming who he really is, even if it's age 64," Berman said. "Because he's getting a conversation in a really public platform that needs to be had."
Berman also points out that who you're sexually attracted too is very distinct from the gender you identify with. In other words, just because Bruce, who now identifies as Caitlyn, may not change other aspects of his life.