Google Drive now lets you see when other people are editing files in Microsoft Office products using Drive File Stream to help with collaboration and avoid version conflicts. When you open a Microsoft Word, PowerPoint or Excel document in Drive, Google checks to see if anyone else is currently editing the document and gives you one of these status reports:

• Safe to edit: No one else is editing. 
• Wait to edit: Other people are editing, so your edits will create multiple, conflicting versions. 
• New version created: Another editor saved a newer version of the file. 
• New version created (conflict): While you were editing the file, another editor also edited it. 

If version conflicts do occur, Drive will show the two versions side by side to help you quickly merge multiple versions into a single, up-to-date document.

Learn more on the Google blog