A trailer is an unpowered vehicle towed by a powered one, usually a car, truck or van. In the United States, it also includes mobile homes with limited living facilities whose owners camp or stay in them when traveling.

A horse trailer is a type of semi-trailer that is used for transporting horses and other livestock. It is designed to accommodate a number of animals, and may have special partitions that protect the animals from injury in transit and help them stay upright. Some horse trailers feature large, open interiors that can be used to house and feed the animals during travel.

Stock trailers are similar to horse trailers but may also be used for transporting other types of livestock. They are often equipped with a tack rack and other storage areas for feed and grooming supplies. They are also available in several sizes, ranging from small units capable of hauling only one or two animals to large semi-trailers capable of hauling hundreds of horses.

The term trailer was originally used to describe horse-drawn wagons, but it has since come to apply to any vehicle towed by another vehicle or pulled by a motorized device. It is sometimes referred to as a utility trailer, and in the United States, it is often used interchangeably with travel trailers and mobile homes.

Depending on the application, a trailer can range in size from a small unit that can be pulled by a pickup or SUV; to large semi-trailers that can haul a significant number of animals. Some larger horse trailers include additional compartments for horses tack and other equipment, and may even feature elaborate living quarters with sleeping areas, bathrooms and kitchens.

Some semi-trailers are designed for hauling heavy loads, and feature lowboy designs that minimize the center of gravity of a load while providing a stable platform to support it. Hydraulic modular trailers are another type of semi-trailer that can be used to carry extremely heavy loads. These use a specially weighted tractor unit, usually with a drawbar to pull or push the load.

A tow bar is a type of hitch that attaches to the chassis of a towing vehicle, or a tow hook that is attached to an aircraft nose gear, for towing a trailer. It is usually a ball-shaped hook that can be rotated to swivel and articulate the trailer or be twisted to turn it.

In the United States, tow bars can be equipped with by-pass relays, which take a small signal from the rear lights of the towing vehicle and switch on a separate electrical circuit for the trailer’s lights. This system allows the tow vehicle’s rear lights to be used by the trailer as well, and eliminates the need for the trailer’s lights to be connected directly to the tow vehicle’s brake and turn indicators.

It is very common for the tow bar of a trailer to be equipped with a jack to lift the trailer when it is not in use, and to lower the trailer when parked or during storage. There are many kinds of jacks, including A-frame, swivel, drop-leg and other types.