Yelp is a multi-national corporation headquartered in San Francisco, California. It develops, hosts and markets Yelp.com and the Yelp mobile app, which publish crowd-sourced reviews about local businesses. The company also trains small businesses to respond to reviews responsibly, hosts social events for reviewers, and provides basic data about businesses, such as hours of operation. Yelp was founded in 2004 by former Paypal employees at the startup incubator MRL Ventures. It was initially an unsuccessful email-based referral service, but was re-launched on the basis of unsolicited online reviews in late 2005. Yelp grew quickly and raised several rounds of funding. By 2010 it had $30 million in revenues and the website had published more than 4.5 million crowd-sourced reviews. From 2009–2012, Yelp expanded throughout Europe and Asia. In 2009 it entered negotiations with Google for a potential acquisition, but a deal was never reached. Yelp became a public company in March 2012 and became profitable for the first time two years later. As of 2014, Yelp.com has 132 million monthly visitors and 57 million reviews. The company’s revenues come from businesses being reviewed on the site paying to advertise. According to BusinessWeek, Yelp has “always had a complicated relationship with small businesses.” Some of the disputes between Yelp and business owners are regarding businesses that fraudulently write reviews on their own locations, accusations of Yelp manipulating reviews to extort advertising spend, concerns about the authenticity of reviews as well as the privacy and freedom of speech of reviewers.