What is a trolleybus? - You may ask. A trolleybus is like an ordinary bus but instead of running on diesel or petrol/gasoline, it runs on electricity by picking up the current by means of an overhead wire. In other words, a vehicle like this is part tram/streetcar, part bus!
London Transport employed trolleybuses between 1931 and 1962. Although such vehicles are no longer in regular service in Britain, they are still in regular service in Russia!