A bus, archaically also omnibus, multibus, or autobus is a road vehicle designed to carry passengers. Buses can have a capacity as high as 300 passengers. The most common type of bus is the single-decker rigid bus, with larger loads carried by double-decker buses and articulated buses, and smaller loads carried by midibuses and minibuses; coaches are used for longer distance services. Bus manufacturing is increasingly globalised, with the same design appearing around the world.

Buses may be used for scheduled bus transport, scheduled coach transport, school transport, private hire, tourism; promotional buses may be used for political campaigns and others are privately operated for a wide range of purposes.

Horse-drawn buses were used from the 1820s, followed by steam buses in the 1830s, and electric trolleybuses in 1882. The first internal combustion engine buses, or motor buses, were used in 1895. Recently there has been growing interest in hybrid electric buses, fuel cell buses, electric buses as well as ones powered by compressed natural gas or bio-diesel.

Etymology
Bus is a clipped form of the Latin word Omnibus. It appeared in Paris in 1819–20 as (voiture) omnibus meaning (carriage) for all, and appeared in London in 1829. One etymology holds that "omnibus" is derived from a hatter's shop which was situated in front of one of the first bus stations in Nantes, France in 1823. "Omnes Omnibus" was a pun on the Latin sounding name of that hatter Omnès: omnes meaning "all" and omnibus means "for all" in Latin. Nantes citizens soon gave the nickname of Omnibus to the vehicle.

History
Early history
A short-lived early public bus line (known as a "Carriage" at that time) was launched by Blaise Pascal in Paris in 1662 and was quite popular until fares were increased and access to the service was restricted to high society members by regulation. Services ceased after 15 years and no further such services were known until the 1820s.

John Greenwood arguably established the first modern omnibus service in 1824. As the keeper of a toll-gate in Pendleton on the Manchester to Liverpool turnpike, he purchased a horse and a cart with several seats and began an omnibus service between those two locations. His pioneering idea was to offer a service where, unlike with a stagecoach, no prior booking was necessary and the driver would pick up or set down passengers anywhere on request. Later on he added daily services to Buxton, Chester, and Sheffield. His line immediately sparked fierce competition and a dense network of omnibus services quickly sprouted in the area, often acting as feeders to the railways. In 1865, Greenwood's company and its competitors amalgamated into the Manchester Carriage Company.

In Nantes, France, a similar service to Greenwood's was established by Stanislas Baudry in 1826 and soon expanded into the Bordeaux region. By 1828 he was licensed by the city authorities of Paris for the provision of ten services throughout the capital. The coaches used along this line were of innovative design; they were capable of transporting as many as two dozen people at a time and had three in-built compartments for the different paying classes. The coaches were commissioned from the English engineer George Shillibeer and were introduced into the streets of Paris in 1827. Shillibeer built another bus for the Quaker Newington Academy for Girls near London; this had a total of twenty-five seats, and entered history as the first school bus.

In parallel to the development of the bus was the invention of the electric trolleybus, typically fed through trolley poles by overhead wires. The Siemens brothers, William in England and Ernst Werner in Germany collaborated on the development of the trolleybus concept. Sir William first proposed the idea in an article to the Journal of the Society of Arts in 1881 as an "...arrangement by which an ordinary omnibus...would have a suspender thrown at intervals from one side of the street to the other, and two wires hanging from these suspenders; allowing contact-rollers to run on these two wires, the current could be conveyed to the tram-car, and back again to the dynamo machine at the station, without the necessity of running upon rails at all."

The first such vehicle, the Electromote, was made by his brother Dr. Ernst Werner von Siemens and presented to the public in 1882 in Halensee, Germany. Although this experimental vehicle fulfilled all the technical criteria of a typical trolleybus, it was dismantled in the same year after the demonstration.

Max Schiemann opened the world's first passenger-carrying trolleybus in 1901 near Dresden, in Germany. Although this system operated only until 1904, Schiemann had developed what is now the standard trolleybus current collection system. In the early days there were a few other methods of current collection. Leeds and Bradford became the first cities to put trolleybuses into service in Great Britain on 20 June 1911.

Motor buses
In Siegerland, Germany two passenger bus lines ran briefly, but unprofitably, in 1895 using a 6 passenger motor carriage developed from the 1893 Benz Viktoria. Another commercial bus line using the same model Benz omnibuses ran for a short time in 1898 in the rural area around Llandudno, Wales.

Daimler also produced one of the earliest motor-bus models in 1898, selling a double-decker bus to the Motor Traction Company for use on the streets of London. The vehicle had a maximum speed of 18 kph and accommodated up to 20 passengers, in an enclosed area below and on an open-air platform above. With the success and popularity of this bus, Daimler expanded production, selling more buses to companies in London and, in 1899, to Stockholm and Speyer.[20] Daimler also entered into a partnership with the British company Milnes and developed a new double-decker in 1902 that became the market standard.

Uses
Public transport
Transit bus, used on public transport bus services, have utilitarian fittings designed for efficient movement of large numbers of people, and often have multiple doors. Coaches are used for longer distance routes. High capacity bus rapid transit services may use the bi-articulated bus or tram style buses such as Wright StreetCar and the Irisbus Civis.

Buses and coach services often operate to a pre-determined published public transport timetable defining the route and the timing, however smaller vehicles may be used on more flexible demand responsive transport services.

Tourism
Buses play a major part in the tourism industry. Tour buses around the world allow tourists to view local attractions or scenery. These are often open-top buses, but can also be by regular bus or coach.

In local sightseeing, City Sightseeing is the largest operator of local tour buses, operating on a franchised basis all over the world. Specialist tour buses are also often owned and operated by safari parks and other theme parks or resorts. Longer distance tours are also carried out by bus, either on a turn up and go basis or through a tour operator, and usually allow disembarkation from the bus to allow touring of sites of interest on foot. These may be day trips or longer excursions incorporating hotel stays. Tour buses will often carry a tour guide, although the driver or a pre-recorded audio commentary may also perform this function. The tour operator may itself be a subsidiary of a bus operating company that operates buses and coaches for other uses, or an independent company that charters buses or coaches. Commuter transport operators may also use their coaches to conduct tours within the target city between the morning and evening commuter transport journey.
 
Student transport
In some countries, particularly the USA and Canada, buses used to transport school children have evolved into a specific design with specified mandatory features. These school buses feature things such as the school bus yellow livery and crossing guards. Other countries may mandate the use of seat belts. As a minimum many countries require that a bus carrying students displays a sign, and may also adopt yellow liveries. Student transport often uses older buses cascaded from service use, retro-fitted with more seats and/or seatbelts. Student transport may be operated by local authorities or private contractors. Schools may also own and operate their own buses for other transport needs, such as class field trips, or to transport associated sports, music or other school groups.

Most public or private buses and coaches, once they have reached the end of their service with one or more operators, are sent to the wrecking yard for breaking up for scrap and spare parts. Some buses, while not economical to keep running as service buses, are often converted in some way for use by the operator, or another user, for purposes other than revenue earning transport. Much like old cars and trucks, buses often pass through a dealership where they can be bought for a price or at auction.

Bus operators will often find it economical to convert retired buses to use as permanent training buses for driver training, rather than taking a regular service bus out of use. Some large operators also converted retired buses into tow bus vehicles, to act as tow trucks. With the outsourcing of maintenance staff and facilities, the increase in company health and safety regulations, and the increasing curb weights of buses, many operators now contract their towing needs to a professional vehicle recovery company.

Some retired buses have been converted to static or mobile cafés, often using historic buses as a tourist attraction. Food is also provided from a catering bus, in which a bus is converted into a mobile canteen and break room. These are commonly seen at external filming locations to feed the cast and crew, and at other large events to feed staff. Another use is as an emergency vehicle, such as high-capacity ambulance bus or mobile command center.

Some organisations adapt and operate playbuses or learning buses to provide a playground or learning environments to children who might not have access to proper play areas. An ex-London Routemaster bus has been converted to a mobile theatre and catwalk fashion show.

Some buses meet a destructive end by being entered in banger races or at demolition derbys. A larger number of old retired buses have also been converted into mobile holiday homes and campers.

Bus preservation
Rather than being scrapped or converted for other uses, sometimes retired buses are saved for preservation. This can be done by individuals, volunteer preservation groups or charitable trusts, museums, or sometimes by the operators themselves as part of a heritage fleet. These buses often need to undergo a degree of vehicle restoration to restore them to their original condition, and will have their livery and other details such as internal notices and rollsigns restored to be authentic to a specific time in the bus's actual history. Some buses that undergo preservation are rescued from a state of great disrepair, but others enter preservation with very little wrong with them. As with other historic vehicles, many preserved buses either in a working or static state form part of the collections of transport museums. Working buses will often be exhibited at rallies and events, and they are also used as charter buses. While many preserved buses are quite old or even vintage, in some cases relatively new examples of a bus type can enter restoration. In-service examples are still in use by other operators. This often happens when a change in design or operating practice, such as the switch to one person operation or low floor technology, renders some buses redundant while still relatively new.