The blog’s creator, Brandon Stanton, has simply walked up to people and asked them permission to photograph them. He also asks them their stories.
He's used this approach to take photos of more than 10,000 strangers in the city and has also published a bestselling book, "Humans of New York."
Over the past five years, the blog has transformed from featuring only pictures to also telling stories.
He explained his fascination with New York, calling the city "amazingly diverse."
"If you're going to exhibit the diversity of the lives and stories on Planet Earth ... I don't think there's any single location that would be easier to do that than New York," he said.
Stanton, 31, is known for his ability to get total strangers to share intimate details of their lives. Instead of using a high-tech recording device, he simply takes notes on his phone.
He says that the first question he asks them is "What is your greatest struggle right now?"
The replies are remarkably candid. People talk in detail about their struggles with money, health, relationships and gender and sexual identity.
Stanton says he believes that their honesty comes from being able to share with someone who doesn't know their story and has no preconceived judgments.
"You know, I think there's something liberating about that," he said.
Stanton's blog has more than 15 million followers – known as the HONY community -- on social media.
Because of the blog's large following, Stanton has been able to raise millions of dollars for people and organizations in need.
Stanton said two fundraisers in the past six months have collected more than $4 million.
"I really think that that is a testament to the type of people that follow Humans of New York," he said.
Stanton just returned from spending time in Europe and speaking first-hand with Syrian refugees. His first question to them was to ask them to recount the day they left Syria.
"They would start speaking in Arabic, and they would stop, and then tears would start coming down their face," he said.
"Humans of New York: Stories" will be released on Tuesday.