Carpooling is seen as a more environmentally friendly and sustainable way to travel as sharing journeys reduces carbon emissions, traffic congestion on the roads, and the need for parking spaces. Authorities often encourage carpooling, especially during high pollution periods and high fuel prices.
Carpool is a popular way to travel in groups in America and Western Europe. It is an arrangement between traveling in one direction using a single car instead of every one to drive alone his car.
By having more people using one vehicle, carpooling reduces each person's travel costs such as fuel costs, tolls, and the stress of driving.
Carpool commuting is more popular for people who work in places with more jobs nearby, and who live in places with higher residential densities.
Carpooling is not always arranged for the whole length of a journey. Especially on long journeys, it is common for passengers to only join for parts of the journey, and give a contribution based on the distance that they travel.
Today most carpooling is organized thanks to fast-emerging online marketplaces that allow drivers and passengers to find a travel match and make a secured transaction to share the planned travel cost. Like other online marketplaces, they use community-based trust mechanisms, such as user-ratings, to create an optimal experience for users.
In an effort to reduce traffic and encourage carpooling, some governments have introduced high-occupancy vehicle (HOV) lanes in which only vehicles with two or more passengers are allowed to drive. HOV lanes can create strong practical incentives for carpooling by reducing travel time and expense.