A driver's license (U.S.), driving licence (UK, Ireland, Hong Kong, India, Pakistan, Singapore, Malta), driver's licence or driver licence (Canada, Australia†, New Zealand), or operator's licence is an official document which states that a person may operate a motorized vehicle, such as a motorcycle, car, truck, or a bus.

History
France and Germany were among the earliest countries to require mandatory driver licensing, right at the start of the 20th century. As automobile-related fatalities soared in North America, public outcry provoked legislators to begin studying the French and German statutes as models.

On August 1, 1910, North America's first driver licensing law went into effect in the U.S. state of New York, though it initially applied only to professional chauffeurs. In July of 1913, the state of New Jersey became the first to require all drivers to pass a mandatory examination before receiving a licence.

Identification
Because a large number of countries, including Australia, Canada, the United Kingdom and the United States have no national identification cards and because of the widespread use of cars, driver's licenses are often used as a de facto standard form of identification.

These U.S. states: Alaska, Arizona, Colorado, Connecticut, Delaware, Florida, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Nevada, New Hampshire, New Jersey, Ohio, Oklahoma, Pennsylvania, Rhode Island, Texas, Virginia, Washington, West Virginia, and Wisconsin require licenses and ID cards issued to those under 21 to have a vertical orientation instead of the usual horizontal one in order to aid in determining whether one is of legal drinking age. California and Oregon have adopted a similar system for its licenses, having the picture appear on the right for drivers under 21 and on the left for drivers 21 and older. New York, on the other hand, prints "Under 21" in red bold letters on the licenses of minor and young adult drivers, but otherwise these licenses look identical to those for older adults. North Carolina recently started a color program for varying age groups: A red border indicates the driver is under 18, a yellow border for ages 18-20, and a green border for those 21 and over, as well as "Under 18" or "Under 21" written down the right side of the driver's picture if they are under 18 or 21. Many states also add information to their licenses, such as "Under 21 until 08-15-2007" to aid in enforcing the drinking age and age of majority of 18 (for tobacco and lottery in most states).

Many European countries and Canada require drivers to produce their licence on demand when driving. In such countries, the driver must always carry their licence on them when driving. In the United Kingdom, when required to produce a driving licence, the driver may have up to 7 days to produce the licence at a Police station.

Many European countries also require adults to carry an ID card at all times. Citizens of EU countries which have no national ID cards also have to carry their passports when traveling in these countries, whether driving or not.

In the People's Republic of China, the driver's licence number is synonymous with the citizen's ID number (which is up to 18 digits long).

Similarly, Saudi Arabia requires all drivers to carry an ID card in addition to a licence, and present them whenever requested. Using a driver's licence instead is only permitted if the request is made for on-site inspection/identification purposes, especially at check points. Expatriates may be requested to present their visas as well.

Many countries have established a driver's licence exchange arrangement after reviews of the foreign jurisdiction's licensing processes. Where standards in the other jurisdiction are comparable in areas such as medical standards, minimum driving age, and knowledge and road testing, an exchange (or honoring) of the foreign jurisdiction's license may occur.

In Hong Kong the driving license has the same number as the HK ID card, yet is without a picture and is always given along with the ID card when being inspected.

Organ donations
Licensing bureaus in many countries add an organ donation option on license forms. Sometimes a small picture of a "heart" or the term Organ Donor is printed on the driver's license to indicate that the holder has agreed to donate his or her organs in the event of sudden death in a car crash or other accident.

In the United States, this is governed by the Uniform Anatomical Gift Act. In the United Kingdom, New Zealand and Ireland, willingness to donate organs for transplantion is also listed on driving licenses. In Australia, the system of notating organ donation requests on licenses was replaced in July 2005 with a national registration system and the issue of special cards.