Groupon was presented by four individuals. It was launched in 2008 as a deal of the day website in Chicago and has since expanded globally. Andrew Mason conceived of the idea, which was developed by Eric Lefkofsky. Groupon's business model involves offering group coupons in each market, working like an assurance contract to reduce risk for retailers. The company earns about 50% of what customers pay. While it provided an online marketing tool and benefits to consumers, its model did not encourage repeat visits. Competitors include LivingSocial, Gilt City, and Amazon Local.