CVS provides a notification scheme which allows a group of developers to know if somebody is working on a given file. This facility is known as watches. By setting a watch on a file, you can have CVS notify you via email if someone else starts to edit this file. This mechanism is notification based only; the file is not locked in any way on the server, and several people are allowed to edit the same file at the same time.
In addition to watch list notification, edit on its own is useful for discovering if others are also editing that file. This is because when you edit a file, you will be informed if someone else is already editing it.
Normally with CVS clients, you would need to issue an explicit edit. With Team CVS support however, an edit is automatically issued by the client when you start to modify a file. In addition, when editing a file, Team CVS provides you with the list of people already editing a file. This allows you to find out who is working on a file before you start to edit it.