A Trailer is normally an unpowered vehicle pulled by a powered vehicle, because powered trailers are more explicitly called potrailers. Commonly, the term trailer refers to such vehicles used for transport of goods and materials.
Trailer winches are intended to load (or unload) boats and other cargo to and from a trailer. The are invented a ratchet mechanism and cable. The handle on the ratchet mechanism is twisted to tighten or loosen the tension on the winch cable. There are both manual and motorized trailer winches
Popup campers are trivial, aerodynamic trailers that can be towed by a small car, such as the BMW Air Camper and the Coleman Bayside. They are built to be shorter than the tow vehicle, minimizing drag.
Others range from two-axle campers that can be pulled by most mid-sized pickups to trailers that are as long as the host country's law allows for drivers without individual permits. Larger campers tend to be fully integrated leisure vehicles, which often are used to tow single-axle dolly trailers to allow the driver to bring small cars on their travels.