Firefox OS is the next product being developed by Mozilla. It's an open source OS based on the web and following the principals which have made the web a success. We'll demo a phone running recent builds of Firefox OS (it's not a finished product yet) and talk about the technologies and ideas behind Firefox OS. Firefox OS is an OS built entirely on web technologies using Open Source Software. Everything the user sees and interacts with is rendered using standard HTML and CSS and all application code is written in javascript, as is the implementation of many of the new APIs which are exposed to applications and web pages. The idea behind Firefox OS is to create an application platform which lets developers use technologies that they are familiar with from the web and that, as much as possible, create a development environment like the one used on the web. This means that to create an app, all you need to do is to set up a normal website and add a bit of metadata in a JSON file. Users can then "install" this website and get an experience similar to that on traditional OSes like Android or Windows. Our ultimate goal is to have a standardized platform that allows for applications that can run on any OS and any device, just like web pages can run on any hardware that has a browser, while staying true to the technologies and philosophies which drive the web. No need to get approval from an app store, and no need to get locked into the platform of a particular vendor. We will demo a phone running recent builds of Firefox OS (it's not a finished product yet), as well as talk about the technologies and ideas behind Firefox OS and our experience building it.