When uploading an asset one of the options available is 'Do not submit yet'. As an uploader, selecting this option means the asset is only available to you until you decide to submit the asset to the application (either for approval or directly live). 

The 'Unsubmitted Assets' page records those assets in one location so that you can edit and update them until you are happy to submit them for other users to view or approve.

The page lists all the unsubmitted assets along with a thumbnail representation of the asset and the actions that can be performed for each asset ('Submit to live', 'Submit for approval' and/or 'Delete').

The page also provides a link to batch update all the current user's unsubmitted assets.