I am getting questions from tourists visiting Prague how to get from the Prague Airport and generally how to use the public transport here.
There is a bus station right in front of the airport terminal. It might be a bit crowded and the tricky part is you need a ticket; it is a part of the city transportation system, so the rules are the same for buses as well as the trams and the metro (underground). If you need just a quick ride, the ticket for 24 CZK/persou should do (it is valid for 30 minutes since registered). Otherwise, the ticket for 32 CZK is recommended (especially when you need to change the lines), which is valid for 90 minutes. It is also possible to buy the whole-day ticket for 110 CZK, if you plan to use a bus/tram/metro more than 3 times that day. You can buy tickets at a desk in the airport building, or there are ticket machines on the bus stop. I think at the airport, there are some more sophisticated ones (normally in the underground and bus stations in the center, you need metal coins to use the machine; here I think it might be possible to use also paper notes or even a credit card but I am not sure).
If you choose to use the bus, just go to the bus stop (you should see it as soon as you leave the airport terminal building). All busses from here go to a metro station (No 119 goes to the metro station Nadrazi Veleslavin of the A line; No. 100 is also OK, it goes to metro station Zlicin on the B line; No. 191 goes to a farther Line B station Andel but it takes too long – like 3 times longer than No. 119 or 100).
In the bus, you need to register the ticket; there are several small machines fixed on the handles/vertical handrails inside the bus, you just insert the ticket inside the machine and wait a second or two; it prints the date and time on the ticket).
Once you come to a metro station by the bus, you can just go in the underground and pick the train you need. You always register the ticket just the first time you start using it, so when changing lines, no registration is necessary. It is possible to change lines freely between trams, buses and metro, as soon as you do not exceed the time limit (i.e. 90 minutes with the ticket for 32 CZK).
There are zones but you do not need to study which zone you are in, the whole Prague is within the inner zones that are covered by the same fare. If you wanted to take a bus to a location outside the city borders, it would cost more but all metro stations and all trams and most buses within the city borders are OK.
If public transport seems too complicated (I think it’s not but it might take some time to get used to it), then there are two more options to get from the airport. There is an express bus line (marked AE) from the airport to the main railway station. It costs more (I think 60 CZK/person, you pay in the bus). The main station is on the metro line C, so you can change here but you would need new tickets (the ones from AE line do not work)
The third option is the taxi. I don’t like them, they usually charge more than they should (either have their meters tampered, or just take you longer way than necessary). You could order an Uber ride but the airport taxi drivers are very hostile to Uber drivers, there even have been some violence in the past, so it might be an unpleasant experience. My son uses Uber all the time, so far so good, I myself prefer the bus.
You can order a taxi using a desk in the airport building; it might help to feel a bit safer but they will rob you anyway 🙂