The portal system provides a few facilities for helping avoid multiple people editing the same page at the same time, and enabling released versions of pages to be preserved, undisturbed, for public view while new versions are being edited and internally reviewed.
There are two layers by which concurrent edits are avoided. Page locking is the lower layer. When someone is editing a page the system marks the status of the page as being locked, so that others concurrently attempting to edit the same page can be alerted to the fact, and avoid inadvertently creating a competing version.
The main reason to know about locks is because abandoning edits to a page without cleanly Cancelling tends to leave the page locked, creating a false caution for the next page editor. The message is that it is best to abandon your edits by using the cancel tab at the bottom of the edit area, rather than just navigating away from the page, so that the page will be marked as unlocked.
If you do encounter a locked page, the locker will be identified. You can contact them if there is any reason to suppose that they do, in fact have edits they're going to soon save. If the lock is days old, it's more than likely that you can just select to "break" the lock and start your edit.
In general you will be using the next layer, checking out a working copy of the page you want to edit, and editing that as a separate document. Check-out and check-in are in the Actions pull-down menu of the content-well edit bar, and pages that have been checked-out are locked and present notices indicating the checkout to visitors with edit privileges. Subsequent check-in by the editor removes the locks and notices, completing the edit.
- publication states - publication status that affects whether or not a page is visible to the general (unauthenticated) visiting public
- versioning - see the revision history of a page, compare versions, resurrect an older version