As with any start-up that ultimately succeeds, Google was founded to solve a problem that was causing the masses pain. In 1999, internet search engines were designed to return pages that had the most instances of keywords. The pages with the highest instances of the keywords were returned first. Web developers used this design to their advantage by loading illogical combinations of words on their pages to create high counts of many words. This resulted in low quality results being returned at the top of searches. By the time Larry Page and Sergey Brin unveiled their PageMark algorithm to power search engines, users were ready for a new solution. PageMark relied on the number of inbound links a site has rather than the number of keyword occurrences to rank results. Brin and Page figured that other web developers had already valued a target site by linking their site to it and so returning targets with the most inbound links at the top. In doing so, PageMark would also return the most valuable sites. The technology quickly caught on and empowered the company to experiment with paid listing models for selling ad space. The focus on innovative ways to grow ad revenue led Google to create AdSense, an advertising system that places ads where users find similar content. AdSense enabled Google to grow beyond search and it quickly became a web-based juggernaut by adding Google Maps, Docs, Finance, and Gmail to name a few. The more free platforms Google delivers to users, the more ways it can sell content based ad space with AdSense.