A night bus service or owl service is a public transport bus service which operates through the nighttime hours. Many cities operate such services, either in addition to or in substitution for ordinary daytime bus services or rapid transit rail services which may shut for maintenance or due to lack of passenger volumes at night.

Twenty-four-hour rapid transit operation is practiced in some cities, which renders these services unneeded. Night bus service is generally much more limited in geographic coverage than daytime services, there are usually fewer lines and routes may run over entirely different paths to daytime services, or the night bus terminus may be in a different place. Some networks may run longer routes than daytime services, which may use interchanges to reach the same outlying districts. Night services usually also run less frequently.

The difference in services may be prefixed with an "N" for Night bus, or otherwise specially branded compared to the daytime services. Another common way of distinguishing them from their daily counterparts are dark-colored line numbers. Some night services may be provided by virtue of operating some routes as 24-hour services. Some cities apply a different night bus fare structure to the daytime services. Some services may allow users to alight at a requested place of stopping rather than at specific bus stops in deference to passenger concerns about safely walking long distances.

A transit bus (US), also known as a commuter bus, city bus, or public bus, is a bus used for short-distance public transport purposes. The roles and specifications of transit buses are not clear cut, and vary with operator and region.

With the development of bus building technologies and urbanisation, the emergence of specific transit bus features emerged for the different operating conditions compared to other private or public transport bus use.

The features of a transit bus are geared for operation on regular urban or suburban bus routes, with multiple defined stops, in a commuting or short-distance leisure role. This is as opposed to all-seated inter-urban or long-distance coach public transport; shuttle buses; demand-responsive buses such as paratransit, or private-hire bus or coach operations. Increasingly, transit buses are built as low-floor vehicles.

Generally, a transit bus will have:

Modern transit buses are also increasingly being equipped with passenger information systems, multimedia entertainment/advertising, and passenger comforts such as heating and air-conditioning (as opposed to historically where actually necessary). Some industry members and commentators promote the idea of making the interior of a transit bus as inviting as a private car, recognising the chief competitor to the transit bus in most markets.