Kolkata has an extensive network of government run and privately run buses. The ticketing system is not centralized one and one has to purchase separate tickets for buses,metros,trams and trains.
There are multiple organisations running buses,a private organisation,and multiple government services like CSTC(Calcutta State Transport Corporation),CTC(Calcutta Tramways Company),WBSTC(West Bengal Surface Transport Corporation) etc. There are also various types of privately run buses.
The private-owned buses are quite typical of Kolkata. The private-owned buses are of two types,the regular ones and the mini-buses. The regular buses are coloured light-blue and yellow. The mini-buses are of brown and yellow colour,and contain lesser number of seats. The mini-buses were started in the late seventies as a relief for the office commuters from the overloaded buses by being a sitting-only service,but this has given way to severely overloaded and crowded mini buses(and other buses too),largely due to the massive population of Kolkata.
The government-run buses are run by several authorities like Calcutta State Transport Corporation(CSTC),South Bengal State Transport Corporation(SBSTC),North Bengal State Transport Corporation(NBSTC),West Bengal Surface Transport Corporation(WBSTC) and the Calcutta Tramways Company(CTC). Government buses have no colour code and can be identified only by the appropriate symbol(CSTC or CTC or WBSTC) on their body. Both the name of the place where the bus is going to,as well as the name of the place where its route originated is mentioned on the bus,- which makes it easy to identify the source and destination of the bus. On the Route Board of the Private/Mini Buses,the ply through(via) stoppages are also mentioned. Further,usually the conductor will call out the names of the stops to come at each halt,so boarding the right bus is not much of a trouble. If in doubt the conductor or any fellow passenger will help out. The buses will often stop to pick up a passenger who waves at the bus.
Recently air-conditioned buses have been introduced by the WBSTC. These buses connects places like the Airport,Santragachchi(a station on the Howrah-Kharagpur railway line) and Tollygunge.
Kolkata is the only city in India to have a tram network. Trams are under the administration of the Calcutta Tramways Company,a government of West Bengal Undertaking,popularly called CTC.