Originally Posted by JulieS

You don't need Project Server to allow people to edit a project file. They will need Project installed - but anyone with access to the file can edit it.

Project server is a true Enterprise Project Management system. If you are a small company, you might want to think about Project Online before going down the road of Project Server. You will also need to purchase Project Professional licenses to work with either Project Server or Project Online.

I hope this helps.