Adapted from Chrome Webstore description
Review and approve changes made to your document
When collaborating on a document, it can be tough to manage the editing process. Track Changes Basic gives you the control you need. You can selectively accept the edits you like, and discard the ones you don’t.
★ Track Changes: Absolutely free way track any change made to your document
★ Manage Changes: Accept or reject changes easily by using the Track Changes sidebar
★ Easy to Review: Changes are color coded for easy review: additions are in green and deletions are in red with strikethrough.
★ Simple Controls: Turn Track Changes on or off and reset tracking with a single click using the Add-ons menu.
★ Secure and Private: No part of your document is ever transmitted or stored outside of Google’s servers.
Video and text taken from Google Docs site; click here to learn more and see comments.