What is Co-authoring Documents in SharePoint

SharePoint Co-authoring documents

SharePoint allows multiple users to work on the same document at the same time, known as Co-authoring. This features helps collaboration and improves user experience and usage of SharePoint.
Types of files to co-author

Below MS Office files can be co-author Documents:

Word
Excel
PowerPoint
OneNote

Enable Co-Authoring

Co-authoring is enabled default in SharePoint Online, manual enable is not required.
Co-Authoring works

In Word

In Word documents is the place where Co-authoring works perfectly. You should note that, it slightly differs in Word Online vs. Native Word Application. The main feature is, if multiple users are modifying the SharePoint documents at the same time, every users are permitted to see the other users presence and they can see the changes happening live.

In Excel

Native Excel app (desktop app) and Excel Online can be used for Co-authoring. It has the similar feature, which are present in word. You will get user presence notifications in the upper right hand corner, also edits can be viewed live.

In PowerPoint

PowerPoint is also a great feature to perform Co-authoring. The features are similar as Word and Excel.

You should note that, it works perfectly for PowerPoint Online and Native PowerPoint app.

Notification in the upper-right-hand corner of PowerPoint native application when another user edits at the same time

In OneNote

OneNote also has the similar feature as Word, Excel and PowerPoint. Multiple user can work on the same document at the same time and changes can be viewed live. It works perfectly with browser editing as well as native applications.

Versioning with Co-Authoring

As mentioned above, a document can be worked by multiple users at the same time. The question, which is raised by the user, is whose name is captured? The answer would be, the user who modifies the SharePoint document at the end and hit the save button, that name is registered in Version History.