There is a difference between saving and publishing your project to Project Server. You will notice that if you attempt to publish your project from MS Project Pro 2003, and you have made changes to the project without saving it, then you will receive a message saying that your project will be saved first, and then published.

Why does this matter? Why isn't saving and publishing the same thing in Project Server? After all, it seems rational that if you save your project, then it should be automatically published to Project Server, since if you publish your project, your project is automatically saved, right?

Well, the answer to this question, at least in part, is that when you are working on a project plan, you will want to save your project from time to time to protect against losing your work. However, you may not have finalized your project plan and want to continue to add information to it, review it, and/or modify it before publishing. Therefore, you save it first, and publish your project only when you believe that it contains enough information that will make it useful to other viewers of the project plan on Project Server.

Another reason that saving and publishing a project plan are distinct is that a "published" project has a very special status in Project Server. A published project is a special kind of version of a project plan. According to the Project Server 2003 Administrator's Guide states that:

"Use the Published version to track all project data during the entire project life cycle. This is the only type of version from which you can publish assignments. This is the version that must be used for all types of project status.

"This version cannot be overwritten, to protect against loss of assignment data. The Published version:

• Cannot be renamed or deleted.
• Is the only version type that can be used as a method of tracking assignment data.
• Must be the initial version of any project published to the Project Server database.
• Is the version of any project published to the Project Server database that is used for reporting and tracking actual work."

To see what goes on behind the scenes in the Project Server database when saving or publishing a project, check out this tip.