After the founders raised $30,000 by selling cereal named after the two candidates of the 2008 United States presidential election, Barack Obama and John McCain, mostly at the 2008 Democratic National Convention,[14][15][16] computer programmer Paul Graham invited the founders to the January 2009 winter training session of his startup incubator, Y Combinator, which provided them with training and $20,000 in funding in exchange for a 6% interest in the company.[10][17][18] With the website already built, they used the Y Combinator investment to fly to New York to meet users and promote the site.[16] They returned to San Francisco with a profitable business model to present to West Coast investors. By March 2009, the site had 10,000 users and 2,500 listings.[19]

In March 2009, the name of the company was shortened to Airbnb.com to eliminate confusion over air mattresses.[10] At the March 2011 South by Southwest conference, Airbnb won the "app" award.[20] In July 2014, Airbnb revealed design revisions to the site and mobile app and introduced a new logo.[21][22] It also announced a partnership with Concur, an expense reporting service for businesses.[23]

In 2014, linguist Mark Liberman criticized the extreme length of the legal agreements that Airbnb members are required to accept, with the site's terms of service, privacy policy, and other policies amounting to "55081 words, or about the size of a short novel, though much less readable".[24]

In April 2015, following the easing of restrictions on U.S. businesses to operate in Cuba, Airbnb expanded to Cuba, making it one of the first U.S. companies to do so.[25][26] In July 2016, former Attorney General Eric Holder was hired to help craft an anti-discrimination policy for Airbnb after reports showed that hosts were refusing to accept lodging requests from guests whose names suggested that they were black.[27] As part of the reform, photos of prospective guests are hidden from hosts until requests for lodging are accepted.[28]