Catalog is another place (a dedicated place) where you can store your bookmarks. To access your Catalog bookmarks select the "Catalog" radio button in the top right corner on the My Bookmarks page.
There are several ways you can use the Catalog:
Option A
If you don't want to use the Dashboard at all, you can store all your bookmarks in the Catalog. In this case make sure to tag your bookmarks so that you can find them later easily.
Option B
You can use the Catalog as a temporary storage as well. When you add a bookmark to Ninja, and don't know which Tab or Category you want to add it to on the Dashboard, simply add it to the Catalog. Later you can move the bookmark from the Catalog to the appropriate Category on the Dashboard.
Option C
You can use the Catalog as an archive to collect the bookmarks that you don't use frequently but you may need later. Simply move these bookmarks from the Dashboard to the Catalog. There is no limit how many bookmarks you can add to the Catalog.