[cloudking]

Google Docs solves this problem. Every revision is auto-saved in the cloud. It's come a long way since it was released 2006, pretty much has fidelity with every major Word feature. Also it's free with a Gmail account.

[krater23]

But there are many things that you don't want to store on a giant software company's computersystems that's specialized on examining data.

[ToFab123]

Word has the same if you save your documents in a folder backed up by OneDrive and you turn on auto save in word.