Mozilla, taking its first foray into the mobile business, will begin rolling out its new Firefox OS this summer. Firefox OS is a smartphone operating system developed by Mozilla that runs entirely on HTML 5, the latest and most advanced programming language for Web browsers. The nonprofit organization known for its Web browser said Firefox OS will first launch in Brazil, Colombia, Hungary, Mexico, Montenegro, Poland, Serbia, Spain and Venezuela. It did not say when it could come to the U.S. Mozilla said it is working with LG, Huawei, Alcatel, and ZTE to build smartphones running Firefox OS. Separately, Sony announced that it is exploring the development of Firefox OS smartphones in partnership with Spain's Telefonica. "Our engineers are now working with Firefox OS Mobile and HTML 5 -- evolving technologies which show great potential," Sony Mobile Communications' Chief Executive Bob Ishida said in a statement. Mozilla said it will also launch the Firefox Marketplace alongside Firefox OS. The Firefox Marketplace is an app store where users will be able to get apps from developers that include Twitter, Facebook, EA Games and Disney Mobile Games. "We're excited about the future of Firefox OS, and look forward to phones shipping with support for our new Twitter app," Twitter said in a blog post about Firefox OS.