The Chrome OS is basically a browser (like Apple's Mac IOS or Windows) that also happens to run your entire computer. Chrome OS has some ‘extras’ that make it more than just a browser. For one, there’s a desktop environment similar to Windows, and you can also use a Chromebook offline. There are more than 200 web apps that work offline for Chrome OS, and most newer Chromebooks run Android apps. You can find a full list of Chromebooks with Android app support here.