In bus advertising, buses and their related infrastructure is a medium commonly used by advertisers to reach the public with their message. Usually, this takes the form of promoting commercial brands, but can also be used for public campaign messages. Buses may also be used as part of a political or promotional campaign, or as a tool in a commercial enterprise. History Bus advertising descends from similar methods used on streetcars in the early 20th century. Infrastructure Adverts are placed in bus shelters. These can be static posters, or back illuminated displays, or rolling displays allowing many messages on one shelter. Technology has also been used to create interactive adverts. Adverts may also be installed on associated street furniture such as the backs of benches at stops. Sized at approximately 2.5 by 6.5 feet, bus bench ads tend to be cheaper per unit than other forms of outdoor mass advertising. Tickets Often, the paper bus ticket is used as an advertising space. The ticket rolls for the ticket machines are pre-printed on the rear with a particular company's advert. Bus interiors A common location for adverts is inside the bus. Adverts are attached to the corners between the walls and ceiling overhead to catch the eye of passengers, in the same manner as used in rapid transit systems. Increasingly, companies are using interior television systems to advertise. The most common technology is the LCD-TFT systems in different resolutions: 18.5" (also side-by-side panels 18,5" + 18,5"), 21.5" and stretched monitors in 29.4". The LCD-TFT were originally installed to show route information to passengers (next-stop, path, maps, intersection with other routes etc.), then additional public information (messages from bus company, the Public Administration, etc.) and entertainment, which is known with the neologism infotainment. It common to use this space for both public information and advertising, providing both a public service but also a regular income for the different players involved in the public transport. Bus exteriors Panels Adverts are often placed as basic rectangular motifs on the side or front of a bus. These may be applied directly to the bus. Additionally, adverts may be printed on placards known as boards, which are slotted into special guide fittings attached to the side of the bus. Partial and full adverts Occasionally, the entire surface of a bus is turned into an advertisement. This can be a whole side or rear of a bus,