Photo by extranoise (Flickr)
Berlin has a multi-modal, interlinked public transport system any world class city would be proud of. The "BVG" connects the city by bus, tram, an underground (the U-Bahn), city trains (the S-Bahn), intercity trains - even by ferry. And it runs on time!
There are three price zones (A, B and C), but unless you travel far outside the S-Bahn “ring” which skirts the city's main districts, an AB ticket (€2.30) covers all of the above-mentioned modes of transport. Unlimited AB day passes cost €6.30; a seven-day AB pass costs €27.20.
If you want to plan a day trip to Potsdam, you can pay a small additional charge to extend tickets to include zone C at BVG ticket desks. For short journeys of no more than three U-Bahn or S-Bahn stops (or no more than six stops on the bus or tram), you can buy a Kurzstrecke ticket for €1.40.
The Berlin CityTourCard is ideal for tourists: it offers includes unlimited transport in the city and big discounts on about 50 attractions.
You will find complete fare information, with an English-language option, here.