Prague has a well organised network of metro, tram and bus lines covering the entire city at almost any time of the day or night.
Metro
There are three metro lines in Prague: A, B and C. Trains are modern, frequent and clean. Prague metro runs from 5 am till midnight.
Tram
Daytime tram lines operate from 5 am till midnight. Between 12:30 am and 4:30 am, main tram lines are serviced by night trams, thus you can easily avoid using taxis in Prague, even in the middle of the night.
Bus
Daytime bus lines operate from 5 am till midnight. Night buses serve routes not covered by night trams. Most probably you will not need to use city buses in Prague, as all important sights can be reached by metro or tram.
Tickets
You can buy Prague public transport tickets from counters at the stations, from machines or from certain news stands. You need to validate your ticket by inserting it into a machine before entering the metro area or as soon as you board a tram or a bus. A ticket which has not been stamped by the machine is invalid. If you get caught by controllers, you will need to pay a fine of 700 CZK (27.5 €) on the spot.
There are different types of tickets available, such as single tickets which do not allow changes of lines and single ticket which do allow changes. If you plan to use public transport in Prague more than once or twice per day, it is worth getting a 24-hrs ticket, which is valid 24 hours from its validation and very convenient to use. It is valid for all forms of public transport in Prague.
Be careful when buying 3-days tickets. When we visited Prague, a 24-hrs ticket cost 100 CZK whereas a 3-days ticket cost 330 CZK. It worked out cheaper to buy 3 separate 24-hrs tickets rather than a 3-days ticket. The reason for the 3-days ticket being more expensive is that it covers an adult and accompanied child aged 6 to 15. So a 3-days ticket would be a better choice for you only if you are visiting Prague with a child aged 6 to 15.
More information: www.dpp.cz