Lane sharing is the practice of operating a vehicle

Vehicle

A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....

 in a traffic lane

Lane

A lane is a part of the roadway within a road marked out for use by a single line of vehicles in such a way as to control and guide drivers for the purpose of reducing traffic conflicts. Most public roads have at least two lanes, one for traffic in each direction, separated by Lane markings...

 in a manner that allows other traffic

Traffic

Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...

 to use the unused portion of the lane, or to pass slower traffic in the lane by using an unused portion of the lane. When lane sharing is done for the purpose of passing slow or stopped congested traffic, it is called filtering forward. When lane sharing is done by using space between lines of traffic, it is called lane splitting

Lane splitting

Lane splitting refers to a two-wheeled vehicle moving between lanes of vehicles that are proceeding in the same direction. More narrowly, it refers to passing stopped or slower moving traffic between lanes at a speed greater than surrounding traffic....

.

Examples of lane sharing

1. A right turning driver moves towards the curb in a wide lane to share the remainder of the lane to his left with overtaking through traffic.
2. Two motorcyclists riding side-by-side in a lane.
3. A dozen cyclists riding in a bunch, or peloton
   Peloton
   The peloton , field, bunch or pack is the large main group of riders in a road bicycle race. Riders in a group save energy by riding close near other riders...
   
   , within a lane.
4. A farm tractor
   Tractor
   A tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...
   
    driver moving over partially into a shoulder to leave room in the lane for overtaking traffic.
5. A cyclist or motorcyclist riding in the unused space surrounding the lane stripe to overtake stopped traffic (filtering forward).
6. A bicyclist riding in the shoulder side of a lane to allow faster traffic to pass on the inward side.

Safety and legality

The safety and legality of lane sharing varies depending on the form of lane sharing being used, and on local traffic laws.