Chrome was the first browser with an extension API based solely on HTML, CSS, and JavaScript. Beta testing for this capability began in 2009,[5][6] and the following year Google opened the Chrome Web Store. As of June 2012, there were 750 million total installs of extensions and other content hosted on the store.[7] In the same year, Chrome overtook Internet Explorer as the world's most popular browser,[8] and its market share continued to grow, reaching 60% in 2018.[9]