The different types of recreational vehicle (RV) trailers can be divided into a few different categories based on size and usage. Most RV trailers can be towed by either bumper or frame hitches on passenger cars and trucks, and they can vary from under 10 to over 30 feet (about 3 to 9 meters) in length. Tent or folding camper trailers are typically at the low end, and some of them are even light enough for a passenger car to tow. Fifth wheel trailers are often some of the longer units, and they require a specialized hitch in the bed of a truck. The biggest RV trailers are commonly known as park models, some of which can be so wide that they require special permits to move.
Many of the smallest RV trailers are referred to as folding or tent units. These trailers typically collapse vertically to about half of their fully expanded height, which provides better aerodynamics and visibility when towing. To set these units up, the top is raised and bunks typically fold out of the front and rear ends. The sides are usually made of canvas or another flexible material, which is why they are often referred to as tent trailers. Similar fold out bunks are sometimes included in larger trailers as well, and full length pop up trailers with rigid sides also exist.
Full sized units are usually referred to as travel trailers. These are rigid sided RVs that can range from small ultralight units to 30 foot (10 meter) trailers that can expand horizontally with slide-out sections. A variation on the travel trailer is the toy hauler. These are similar in appearance to other RV trailers, but the back wall folds out into a ramp. This can allow motorcycles, all terrain vehicles (ATVs), and other equipment to load into the living space of the trailer for easy transport.
Fifth wheel trailers resemble regular travel trailers but they do not hook up to a regular bumper or frame mounted hitch. These trailers require a fifth wheel hitch, which is a special receiver that can be installed in the bed of a pickup. The internal floor plan of these RV trailers typically consists of two levels, with stairs that lead up to the part of the unit that sits over the truck bed.
The very largest RV trailers are commonly referred to as park models. Some of these units can be transported by regular light trucks, though they typically do not have 12 volt electrical systems or self contained plumbing. The largest park models are too wide to travel on most roads, so special permits and signs can be required to transport them. Unlike other trailers that are designed to be moved frequently and allow self contained camping, park models are usually transported less frequently and only used in RV parks, building sites, and other areas where utilities are available.