An intercity bus service or intercity coach service, also called a long-distance, express, over-the-road, commercial, long-haul, or highway bus or coach service, is a public transport service using coaches to carry passengers significant distances between different cities, towns, or other populated areas. Unlike a transit bus service, which has frequent stops throughout a city or town, an intercity bus service generally has a single stop at one location in or near a city, and travels long distances without stopping at all. Intercity bus services may be operated by government agencies or private industry, for profit and not for profit. Intercity coach travel can serve areas or countries with no train services, or may be set up to compete with trains by providing a more flexible or cheaper alternative.

A bus is a road vehicle that carries significantly more passengers than an average car or van, but less than the average rail transport. It is most commonly used in public transport, but is also in use for charter purposes, or through private ownership. Although the average bus carries between 30 and 100 passengers, some buses have a capacity of up to 300 passengers. The most common type is the single-deck rigid bus, with double-decker and articulated buses carrying larger loads, and midibuses and minibuses carrying smaller loads. Coaches are used for longer-distance services. Many types of buses, such as city transit buses and inter-city coaches, charge a fare. Other types, such as elementary or secondary school buses or shuttle buses within a post-secondary education campus, are free. In many jurisdictions, bus drivers require a special large vehicle licence above and beyond a regular driving licence.