Putting the user in control provides many inherent benefits. Design and development documents can be checked in and out, versions of documents and edits made to them can be tracked and managed, and management can be notified of document alterations and modifications using existing tools. SharePoint Portal Server uses role-based security that sits on top of the Windows NT and Windows 2000 security models. As a result, organizations can implement document-management security without impacting or depending on the organization's broader security account or group infrastructure. The security roles allow users to be classified as coordinators, authors, and readers.
Readers can only view the latest published version of a document.
This way, users aren't shown items they don't have permissions to. This tight integration with existing domain-access permissions greatly simplifies information dissemination. You don't need to do any special coding or create folder structures to limit access. SharePoint Portal Server has document-versioning, approval, and publishing capabilities. Users are able to check documents in and out, rollback versions, and submit documents for approval and eventual publishing from familiar Office products and the Windows Explorer.