Google Docs is an online word processor and part of the free, web-based Google Docs Editors suite offered by Google. Google Docs is accessible via a web browser as a web-based application and is also available as a mobile app on Android and iOS and as a desktop application on Google's ChromeOS.

Google Docs allows users to create and edit documents online while collaborating with users in real-time. Edits are tracked by the user making the edit, with a revision history presenting changes. An editor's position is highlighted with an editor-specific color and cursor, and a permissions system regulates what users can do. Updates have introduced features using machine learning, including "Explore", offering search results based on the contents of a document, and "Action items", allowing users to assign tasks to other users.

Google Docs supports opening and saving documents in the standard OpenDocument format as well as in Rich text format, plain Unicode text, zipped HTML, and Microsoft Word. Exporting to PDF and EPUB formats is implemented. Google Docs now also supports downloading files in Markdown format.

Google Docs originated from Writely, a web-based word processor created by the software company Upstartle and launched in August 2005. It began as an experiment by programmers Sam Schillace, Steve Newman, and Claudia Carpenter, trying out the then-new Ajax technology and the "ContentEditable" HTML feature. On March 9, 2006, Google announced that it had acquired Upstartle. Google would release a new product, based on Writely, called Google documents on October 10, 2006. In July 2009, Google dropped the beta testing status from Google Docs. In March 2010, Google acquired DocVerse, an online document collaboration company. DocVerse allowed multiple users to collaborate online on Microsoft Word documents, like other Microsoft Office formats, such as Excel and PowerPoint. Improvements based on DocVerse were announced and deployed in April 2010. In June 2012, Google acquired Quickoffice, a freeware proprietary productivity suite for mobile devices. In October 2012, Google renamed the Google Drive products, and Google Documents became Google Docs. At the same time, Google Chrome App versions of Google Docs, Google Sheets, and Google Slides were released, which provided shortcuts to the service on Chrome's new tab page. In February 2019, Google announced grammar suggestions in Docs, expanding their spell check using machine translation techniques to help catch tricky grammatical errors. In March 2023, Google Docs, with Slides and Sheets, introduced a new UI theme.

Google Docs is available as a web application supported on Google Chrome, Firefox, Microsoft Edge, and Safari web browsers. Users can access all Docs, as well as other files, collectively through the Google Drive website. In June 2014, Google rolled out a dedicated website homepage for Docs that contains only files created with the service. In 2014, Google launched a dedicated mobile app for Docs on the Android and iOS mobile operating systems. The mobile website for Docs was updated in 2015 with a "simpler, more uniform" interface, and while users can read files through the mobile websites, users trying to edit will be redirected towards the dedicated mobile app, thus preventing editing on the mobile web.

Google Docs and the other apps in the Google Drive suite serve as a tool for collaborative editing of documents in real time. Documents can be shared, opened, and edited by multiple users simultaneously, and users can see character-by-character changes as other collaborators make edits. Changes are automatically saved to Google's servers, and a revision history is automatically kept so past edits may be viewed and reverted. To resolve concurrent edits from different users, Google Docs uses an operational transformation method based on the Jupiter algorithm, where the document is stored as a list of changes.

An editor's current position is represented with an editor-specific color/cursor, so if another editor happens to be viewing that part of the document, they can see edits as they occur. A sidebar chat functionality allows collaborators to discuss edits. The revision history allows users to see the additions made to a document, with each author distinguished by color. Only adjacent revisions can be compared, and users cannot control how frequently revisions are saved. Files can be exported to a user's local computer in a variety of formats (ODF, HTML, PDF, RTF, Text, Office Open XML).

In March 2014, Google introduced add-ons, new tools from third-party developers that add more features to Google Docs. To view and edit documents offline on a computer, users need to use the Google Chrome web browser. A Chrome extension, Google Docs Offline, allows users to enable offline support for Docs files on the Google Drive website. The Android and iOS apps natively support offline editing.