The Chromebook is a new, faster computer. It starts in seconds, and offers thousands of apps. It has built-in virus protection, and backs up your stuff in the cloud.
A Chromebook is a laptop running the Linux-based Chrome OS as its operating system. The devices were originally designed to be used primarily while connected to the Internet, with most applications and data residing in "the cloud". The original Chromebook was an example of a thin client. However, since its original release, Google Apps (gmail, docs, (spread)sheets, and slides) were rewritten to run in offline mode, and Android Apps are being made available on Chromebooks, which makes the platform more general-purpose than a typical thin client.
The first Chromebooks for sale, by Acer Inc. and Samsung, began shipping on June 15, 2011. In addition to laptop models, a desktop version, called a Chromebox, was introduced in May 2012, and an "all-in-one" device was introduced in January 2014, by LG Electronics.