In general, mobile homes refer to prefabricated home structures that are then transported to a living site. Mobile home structures are movable, and may include RVs, campers or motorhomes. In response to their growing popularity as permanent living options, the U.S. Department of Housing and Urban Development (HUD) developed new safety standards for the construction of these homes, classifying those built after June 15, 1976 as manufactured homes. Manufactured homes have stricter building specifications around aspects such as the frame, insulation and other safety concerns.