Driving is the controlled operation of a land vehicle, usually a motor vehicle such as a truck, bus, or car. Although direct operation of a bicycle, a mounted animal (not including chariot operation) or a motorcycle (at least in the United Kingdom, the United States and Canada) is commonly called riding, such operators are usually considered to be drivers in a legal sense and required to obey those rules of the road which apply to all drivers.
Driving as a physical skill
Driver error is an important factor in collisions, which result in the death of many thousands of people annually (see also car accident). Preventing collisions involves more than just following the rules of the road literally; defensive driving also involves the cultivation of good habits, maintaining attention, and a thoughtful, cooperative attitude.
Avoiding or successfully handling an emergency driving situation can involve any of the following skills:

Reversing
Decision making
Evasive maneuvers
Inflating the tires properly
Pursuit driving
Proper hand placement and seating position
Skid control
Steering and braking techniques
Understanding vehicle dynamics Driving as a mental skill
In most countries, the use of public roads is heavily governed by law. Laws cover the construction and maintenance of roads, the construction and use of vehicles, the rules of the road, the requirements for motorist licensing (see Driver's license), vehicle registration (see License plate), vehicle taxation, safety inspections and compulsory insurance for heavy motor vehicles. These laws reflect the high degree of responsibility which is imposed upon both the drivers and manufacturers of vehicles (especially heavy motor vehicles) to make them as safe in use as they can possibly be.
Motorists are almost universally required to take lessons with an approved instructor and pass a driving test before being granted a license. The trend has been towards increasingly tougher tests in recent decades. Almost all countries allow all adults with good vision to apply to take a driving test and, if successful, to drive on public roads. Saudi Arabia, however, bans women from driving vehicles (whether pedal or motor powered) on public roads. Saudi women have periodically staged driving protests against these restrictions.
In many countries, even after passing one's driving test, new motorists may be initially subject to special restrictions. For example, in Australia, novice drivers are required to carry "P" ("provisional") plates, and are subject to lower speed limits, alcohol limits, and other restrictions for their first two years of driving. This varies between states.

Driving laws
Each country has its own unique way of dividing up the responsibility for enforcing all the laws mentioned above. In nearly all countries, though, the laws controlling driving in practice (like speed limits) are enforced by the police, who are in the best position to identify violations as they occur and to issue citations or make arrests.
Some countries, like Australia, prefer to put everything road-related into a single agency at the state level. Thus, in the Australian state of New South Wales, the Roads and Traffic Authority (RTA) is responsible for driver licensing; highway construction, maintenance, and patrol; and many other things. Policing on Australian roads is provided by the relevant state police.
In contrast, in the United States, many U.S. state governments have a Department of Transportation that handles road construction and maintenance (subject to some guidance from the federal Department of Transportation), and a separate Department of Motor Vehicles that handles driver licensing and vehicle registration. There is usually a state police agency (called the Highway Patrol, State Police, State Troopers or Department of Public Safety) which enforces driving laws on state highways. On local roads, driving laws are enforced by county sheriff's departments or city police departments.
Except for a few jurisdictions, bicyclists are legally treated as drivers of vehicles and expected to cycle vehicularly. Drivers of bicycles are almost never subject to licensing. However, some municipalities do require permits for bicycles.

Minimum motorist ages

Back seat driver
Chauffeur
Driverless car
Driving pleasure
Driving on the left or right
Driving under the influence
Graduated driver licensing
Heel-and-Toe
Highway Code (official road safety manual for the United Kingdom)
Highway patrol
Institute of Advanced Motorists
Mobile phones and driving safety
Road safety
Road racing
Road rage
Sleep Deprived Driving
Traffic jam
Traffic sign
Railroad engineer
Vehicle dynamics