Chrome OS is actually a tiny version of Linux underneath the Chrome browser. According to some sources the original idea was a Linux that could exist totally in RAM for superfast operation. While originally a pure thin client with all of the apps external to the device it now has added several native apps that permit it to do some useful work offline. In 2009 Google announced Chrome OS and actually released an Open Source OS called Chromium OS, however Chrome OS is not Open Source. The first release was based on Gentoo Linux in 2010 but was continued development as an independent implementation of Linux. As of 2014 Google has announced a plan to make it be able to run Android apps, since they are both Linux based. In October 2017 they have delivered on that promise with Google Pixelbook.
Unlike Android and other OS's the Chrome OS is automatically updated to the latest version.
Currently the Chrome OS is available on Chromebook, a netbook style computer. There are models available from Samsung, Acer, HP and Lenovo. It is also be basis of Google TV. The Open Source Chromium OS can be installed on a regular PC. These units will generally have a 1080P screen resolution and have battery lives of up to 12 hours. See Chromebook for more hardware information.
 Web Browser
The Web browser and therefore a part of Chrome OS is a HTML transfer protocol called SPDY (pronounced SPeeDY) which compresses and streamlines the transfer of data. See SPDY whitepaper and Wikipedia for more details. Note this is also supported in Firefox OS. Note that this is being replaced by HTTP/2.
 Chrome OS review
From Endgadget: Chrome OS has come a long way since we reviewed the original Pixel, back in February 2013. First off, most every Google app has offline access, including Gmail, Drive, Music and Google Play Movies & TV. Many third-party apps, such as Pocket and Amazon Kindle Cloud Reader, now work offline, too. In fact, the selection is big enough that there's even a section of the Chrome Web Store dedicated to offline-capable apps. In short, then, the idea that Chromebooks are crippled without an internet connection is a big fat myth. I will say this, though, there is nothing more infuriating than being locked out of a Chromebook during a flight because you have two-factor authentication and can't receive your six-digit code over SMS. That happened to me while testing another Chrome OS laptop recently and, well, let's just say I won't be making that mistake again. Always have backup codes handy.
 Android compatible
Google has released an update for its Chrome OS that enables select Chromebooks to run apps designed for Google Android and access Google Play Store. Right now, only two mobile PCs makers, Acer and ASUS, offer compatible products with the new build. The Acer Chromebook Tab 10, the Acer R11 2-in-1 tablet.
The fact of this release confirms Google’s intentions to enable Android software on its OS for PCs.
 Reading apps
See https://chrome.google.com/webstore/category/app/45-books for more.
- BookFusion - Provides a web reader that allows you to read PDF, EPUB , MOBI and other format eBooks in ChromeOS. They also have a native android app
- Magic Scroll eBook Reader
- audlibri Player - listen to your eBooks
- Blurb Bookify - make and read books made from images.
- SoopBook - a writing online program
- Google Books - The Google collection.
- MeeGenius! children's books.
- specialize collections.
- Overdrive - checkout and read eBooks
- Kindle Cloud reader
- Readium - ePub 3 Reader.
- Rage comics - comic book reader
- Wallabag can capture a web site for offline reading. It is free.
- EBook offline reader
Many Readers permit offline use.
 Google TV
Google TV is a specialized instance of Chrome OS. It is built into some SmartTV's and can also be purchased as an addon box for any TV from several companies. Google TV inserts itself between your cable provider or satellite provider output (HDMI) and has an independent wireless access to your router.
It can support many Android apps and provides a connection to the Google Play store for media streaming and app download.