Add Track Changes to Word Online
This would be one of the most common ways you'd want to collaborate on a document. It is the equivalent of Google doc's "suggesting" mode and without it our organisation would find it extremely difficult to take the plunge and jump ships.
Thanks for the feedback and votes. This feature is in-progress.
Chennah Heroor [MSFT] commented
Thank you for your suggestion! We will consider adding a "Suggestion Mode" to a future update for Word Online. In the meantime, the "Track Changes" feature is available in Word Desktop. You can use the feature to keep track of changes made to your document. This feature allows you to "Accept" an edit to incorporate it into the document, or "Reject" an edit to remove it from the document.
Nick Newman commented
Tracked changes should like like they do in the stand alone version of Word.
Word online can already track changes if it was previously turned on, but why can't it turn the feature on its self?