The ability for multiple people to edit the same document at the same time has been available on a number of platforms for a while now. Google is probably the most widely recognised system that supports this ability but you may not realise that Microsoft Office products also support the same ability.
Office Online, available via Office 365 and from consumer services like OneDrive, allows the ability for multiple concurrent authors of a document in real time. In many cases these co-authoring abilities have been restricted to purely web versions of Office, however Microsoft will be bringing this co-authoring ability to the desktop with Office 2016.
You can now in fact test this co-authoring ability directly from the desktop using the Office 2016 preview when using Word and SharePoint Team Sites or OneDrive for Business. Microsoft provided details in a recent blog post:
Remember that Office 2016 is still in preview and not supported as yet so it should only be used on test systems. However, Microsoft is putting the final touches to the product and it is expected to be rolled out very soon (the Mac version of Office 2016 is already available). If you are an Office 365 user that provides a desktop license you will receive a free upgrade when it is available directly from the Office 365 portal.
Now all this document co-authoring sounds handy but is it really so in practice? My experience is that it is very distracting seeing others working on a document in real time. Perhaps where everyone is together in a single room working collaboratively it makes sense but there is a very powerful desire to exit the document when someone else enters and starts editing.
So yes, the ability to have document co-authoring is an interesting feature to incorporate but in reality does it help your productivity? The jury is still out, at least for me.