Penn created many of the stark, glossy pictures of stick-thin fashion models that appeared in Vogue. He also made portraits of nudes, celebrities and also everyday objects, like cigarettes.
Photojournalist Robert Nickelsberg has been documenting Afghanistan since 1988. A retrospective in Kabul from his book, A Distant War, takes his photos back to the country where he made them.
Brandon Stanton left a life in finance for an entirely different quest: to snap the portraits of 10,000 people. The project eventually became Humans of New York, a blog and the basis for two books.
The 4-inch-by-5-inch tintype depicts Billy the Kid playing croquet in the summer of 1878. The only other known photo of the outlaw was taken in 1880 and sold for $2.3 million in 2010.
Images of the "starving child" were popular in 1980s campaigns. Critics didn't like the depiction of the developing world as a place of helpless victims. Such ads faded away, but now they're back.
Photographer LaToya Ruby Frazier is the third generation of her family to grow up in Braddock, Pa. For years, she says, African-American contributions to the town have been "overlooked and ignored."