Collaborating Around Forms
Following are the tools in each document using which you can collaborate with other Users in your ERPNext account.
If some document requires an action from User, you can Assign that document to that User. On assignment, User to whom document is assigned is intimated via email. To learn about Assign To feature, click here.
Comments are a great way to add information about a transaction that is not a part of the transactions. Like some background information etc.
You can share document with the specific User. If Document is shared with the specific User, he/she will be able to access it, even if that User doesn't have permission to access that document or Document Type.