A U-turn in driving refers to performing a 180° rotation to reverse the direction of travel. It is called a "U-turn" because the maneuver looks like the letter U. In some areas, the maneuver is illegal, while in others, it is treated as a more ordinary turn, merely extended. In still other areas, lanes are occasionally marked "U-turn permitted" or even "U-turn only."
Occasionally, on a divided highway, special U-turn ramps exist to allow traffic to make a U-turn, though often their use is restricted to emergency and police vehicles only.
In the United States, U-turn regulations vary by state: in Indiana U-turns are allowed as long as the driver follows all of the precautions normally ascribed to making a left turn (yielding right-of-way, etc.). Many places, including Texas and Georgia, have specially designed U-turn lanes (referred to as Texas U-turn lanes). In Michigan, U-turns are required for many left turns to and from divided highways, as part of the Michigan left maneuver.
In some special situations, U-turns can be regulated through the use of a traffic light, where it is the only directional choice and drivers in the specified lane cannot continue forward (“U-turn only” lanes).
U-turns are often prohibited for various reasons. Sometimes a sign indicates the legality of U-turns. However, traffic regulations in many jurisdictions specifically prohibit certain types of U-turns. Laws vary by jurisdiction as to when a U-turn may or may not be legal. Examples of jurisdictions with codified U-turn prohibitions include the Canadian provinces of Alberta and British Columbia and the U.S. states of Colorado  and Oregon. In Alberta, U-turns are prohibited in certain circumstances, for example (ref. Alberta Regulation 304/2002, Division 7):
In Taiwan, Article 49 of the Act Governing the Punishment of Violation of Road traffic Regulations (zh:道路交通管理處罰條例) administratively fines a motorist 600 to 1800 new Taiwan dollars for any of the following unlawful U-turn:
In addition, a Taiwanese driver license is demerited one point for an unlawful U-turn pursuant to Article 63 of the same Act unless the license has been suspended or revoked. Furthermore, the same Act makes a U-turn on a railway level crossing a violation for drivers of motorized and non-motorized vehicles: