Google Docs originated from web-based word processor Writely. The app would lay the groundwork for such common features as collaborative text editing. Eventually acquired by Google, it was made available to all Google Apps users in February of 2007.
The marquee feature of Docs is the ability to collaborate with a wide number of people online. Controls help determine who can see, comment, and edit documents. In its current form, Docs is an HTML5 app that runs on most modern browsers and even has support for rudimentary viewing on mobile. Its Android and iOS apps are quite powerful and gives users access to the same web functionality.
On Chrome, Docs works offline and allows users to work without an internet connection and have changes synced backed up to the cloud. An Add-ons feature allows third-party developers to add extra functionality like a thesaurus and a bibliography creator.