Ride sharing is an alternative to hitchhiking.
Like hitchhiking, it involves seeking a ride in a vehicle operated by another traveller who is going to the same destination. Unlike hitchhiking, the arrangements are usually made in advance; the passenger makes some token payment to the driver to defray or partially defray the cost of the trip.
Ridesharing means more ecological and economical transport compared to single occupancy car travel as more than one person ride in a vehicle meaning less consumption of fuel per person transport kilometer and enabling higher traffic density. These services have mobile optimized webapps and also many have native mobile apps.
In some countries the legal status of ride sharing with any compensation to the driver is unclear, as it may be regarded as an illegal taxi. The probability of problems for a passenger is low, but if you are going to offer ride sharing for money, you should check this. As licensing taxis is in the jurisdiction of local municipalities in many places, the situation can vary drastically from city to city.
Various Peer-to-peer ridesharing media are useful to locate prospective drivers or passengers for ride sharing:
Adhoc "split the gas money and be social" real-time via mobile and webapp. Both enabled by ubiquity of mobile communication networks.
Slugging is a term originating in 1990s USA where authorities designate appropriate places as slug line location where people can hang out expecting some rides being offered.
The service of matching drivers and vehicles to passengers could be done from a bricks-and-mortar office. In some jurisdictions, intercity bus companies have lobbied to prevent commercial ride sharing agencies in order to eliminate what they perceive to be a competitor.
A few websites and specialised apps provided "flightsharing", ride sharing with private pilots in general aviation. Many of these were US-based and shut down after a lengthy 2014-15 legal battle in which the US Federal Aviation Administration sought to apply the same regulations to ridesharing as to commercial charter operators with professional commercial pilots.
Ride sharing is most likely to be successful between major centres or popular, beaten-path destinations. On long trips, such as a cross-country Trans-Canada Highway run, passengers may be asked to do some of the long haul driving. It's best to post a request for transportation well in advance and start checking for offer listings at least a week prior to the desired departure dates. It also helps to be flexible with departure and arrival times. As with hitchhiking, some common sense and discretion is advisable.
Ride sharing is not to be confused with: