Catalogs lets you organize images without moving them from a directory to another. The following is the list of operations you can perform with a catalog :
Viewing the list of catalogs : Press Ctrl-2 or select the View->Hide/Show Catalog command.
Adding images to a catalog : Select the images you want to add to a catalog and use the Edit-> Add to Catalog command to select or create a catalog.
Deleting images from a catalog : Select the images you want to delete then use the Edit-> Delete from Catalog command.
Renaming, Deleting or Moving catalogs : Select the catalog and use the Edit->Edit catalog menu, or use the context menu pressing the right mouse button on the name of the catalog in the catalog list.
If you want to go to the directory that contains an image, select the image and use the Go->Go to Container Directory command.