Google Chrome OS
Google Chrome OS is a cloud based operating system for notebooks and netbooks. It is only available pre-installed by hardware manufacturers as well as Google's own laptop, called Chromebook. Like network computers of old, dumb terminals, these lack a hard disk for storage. All files are stored on the web and are accessible by Apps. The Chrome OS uses the Google Chrome browser. Chrome OS is built on the Linux kernel just like their Google Android OS. Applications were once designed for one or the other but have since been made compatible. Google has indicated that they will merge both Chrome OS and Android OS in the near future.
An open source version is available for download, it's called the Chromium OS project.
Chromebooks feature developer mode, which only advanced users will find, and wipes the Chromebook. One should be responsible when running a Chromebook in developer mode, or they will lose data and/or mess things up..
Cub OS (formerly Chromixium) has created a Linux distribution that mimics the look of Chrome OS and is based on Ubuntu. A major advantage is having a hard disk for local storage and customization of Linux properties.
It is possible to install Ubuntu on a Chromebook using ChrUbuntu, but it may be preferred to use Crouton to install an Ubuntu environment. In the latter case, it is two environments, one Chrome OS and one Ubuntu, on one kernel, and one can switch between Ubuntu and Chrome OS seamlessly. Developer mode is required for either case.
