A secret sub-neighborhood, also known as a "stealth neighborhood" or "stealth hood", is a special type of sub-neighborhood, first introduced in The Sims 2: Pets. Secret sub-neighborhoods primarily add new families in the family bin, new NPCs, townies, and secret lots. Some secret sub-neighborhoods can be visited, though the lots are not editable, and none of them can be lived in. Secret sub-neighborhoods do not appear in the sub-hood selection at the top of the screen, and are only referenced in the loading screen when playing a neighborhood that does not have all secret sub-hoods attached.