It's a simple idea: Take a candid portrait of someone on the street, and tell an authentic story about his or her life.
The idea first came from the Humans of New York Facebook page, which was created by Brandon Stanton in 2010. Since then, "Humans of" pages from around the world have been cropping up online since 2012.
Each collecting more than 50,000 likes, "Humans of" Rome, Amsterdam, Karachi, Tehran and India are prime examples of sites modeled after HONY. Most of the sites show the work of emerging photographers documenting their native cities.
"Humans of New York inspired me by giving me the courage to do something that I've always wanted to do . It made me think, 'If someone did it, that means it's possible,'" said Humans of Rome founder Marco Massa, 21, who photographs all of the page's images.
Debra Barraud, founder of Humans of Amsterdam, is also inspired by the other "Humans of" sites, but said she tries to add her "own style of photography to the project."
Thanks to Facebook, the "Humans of" pages are now part of a growing photography community that is gaining global feedback and followers. Facebook is the main platform for the "Humans of" pages, although some chapters, including HONY and Humans of Tehran, have separate websites.
Shirin Barghi, a co-founder of Humans of Tehran, describes Facebook as a core tool for global engagement. "I believe Facebook has made the process of content creation and distribution a great deal more manageable, and has brought users inside and outside Iran into the same space. It's exciting to see Tehran interact with other cities across the world," Barghi told Mashable in an email.
Facebook and Twitter are censored in Iran, but the local online community still manages to access social sites through VPN technology or other tools that redirect servers outside of the country. Humans of Tehran has more than 45,000 followers on Facebook, and Barghi said the page's mission is to present "on-the-ground narratives to build a new visual vocabulary through which the world can communicate and connect with Iranians, who have been politically, and in many other ways, isolated in recent years."
In both Iran and Pakistan, photographers encounter more backlash due to the countries' conservative social and religious norms.
Khaula Jamil, founder of Humans of Karachi in Pakistan, said women are more hesitant to be photographed since male family members can be protective and wary of strangers who speak to them. In Pakistan, the media has a negative reputation for invading people's privacy, Jamil added.
"The Pakistani public generally shies away from anything related to media mainly because journalism has been abused quite a bit by some unethical people in the business," Jamil told Mashable in an email.
Despite some subjects' occasional reluctance to participate, "Humans of" photographers in more underreported regions aim to show authentic images that are rarely seen by the international community.
Megha Majumder, founder of Humans of India, emphasized the importance of genuinely relating to people when photographing them.
"There's this word that I fell in love with a while back: sonder. It's the realization that every random passerby is living a life that is as vivid and intricate as your own, complete with their own thoughts, feelings and emotions. And to them, you're just a passing figure on the street, too. Sonder seized my awareness –- people were no longer just strangers," Majumder, 17, told Mashable.
When Stanton was asked about the other "Humans of" sites in an interview with Mashable's Beckett Mufson, he said that it influences him to pay more attention to his own photography.
"I think the best thing that I can do is to focus on my own work, and focus improving my own photography. The bigger Humans of New York gets and the more followers there are and the more people that are replicating it in their own cities, the more I focus on what I can control, which is my photography and my storytelling."
Image: Humans of Karachi