A pending changelist stores information about files you are working on. There are two kinds of pending changelists: the default changelist, and numbered pending changelists. Your workspace automatically has one default changelist. You can optionally create one or more numbered pending changelists in your workspace.
To see a list of your pending changelists, use Go To -> Pending Changelists. Click on any changelist on this page to view detailed information about it. From there you can edit the changelist, move files from it to another pending changelist, submit the changelist, or delete it. For more information about these tasks, see Editing a Pending Changelist.