Can you "program" a document so that users on the same network can make changes to it at the same time? - changes at vagaina before menstruation

I want to be able to a Word document or Excel with a colleague who works in another computer share (but we) are on the same network. Both can access this document, it opens the second is not changed, if open to the other person. Is there a way to change the document so that we can access both, and change it from different computers?