A roof rack is a set of bars secured to the roof of a motor car

Automobile

An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...

. It is used to carry bulky items such as luggage

Luggage

Baggage is any number of bags, cases and containers which hold a traveller's articles during transit.Luggage is more or less the same concept as "baggage", but is normally used in relation to the personal luggage of a specific person or persons Baggage is any number of bags, cases and containers...

, bicycle

Bicycle

A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....

s, canoe

Canoe

A canoe or Canadian canoe is a small narrow boat, typically human-powered, though it may also be powered by sails or small electric or gas motors. Canoes are usually pointed at both bow and stern and are normally open on top, but can be decked over A canoe (North American English) or Canadian...

s, kayak

Kayak

A kayak is a small, relatively narrow, human-powered boat primarily designed to be manually propelled by means of a double blade paddle.The traditional kayak has a covered deck and one or more cockpits, each seating one paddler...

s, ski

Ski

A ski is a long, flat device worn on the foot, usually attached through a boot, designed to help the wearer slide smoothly over snow. Originally intended as an aid to travel in snowy regions, they are now mainly used for recreational and sporting purposes...

s, or various carriers and containers.

There is a long history of the use of roof racks and their designs. They allow users of an automobile to transport objects on the roof of the vehicle without reducing interior space for occupants, or the cargo area volume limits such as in the typical car's trunk

Trunk (automobile)

The trunk or boot of an automobile or car is the vehicle's main storage, luggage, or cargo compartment. Trunk is used in North American English and Jamaican English; boot is used elsewhere in the English speaking world. Trunk is also primarily used in many non-English speaking regions, such as...

design.

The three most common components of a roof rack system are (side) rails (or tracks), towers which clamp or otherwise attach to the rails, and mounts, which secure the bulky items to the rack system.

Older roof racks were usually mounted directly to the gutter surrounding the roof line. More modern vehicles, which do not have gutters, can often have a roof rack installed by attaching hooks to the top of the door frames.

Some automobiles have fittings for proprietary racks which mate with reinforced lugs in the roof. Other vehicles have a factory-installed permanent roof rack.