Budapest has an extensive public transportation system consisting of bus, tram, and metro (and regional/international rail outside of the city). Within the city, all of these systems use the same form of payment: Tickets.
Now let me explain this very erroneous system of collecting payment. You are asked to purchase a ticket or book of tickets, and upon entering one of these, you need to enter your ticket into a little orange machine for validation.
Once the ticket is validated, it is good for one, one-way trip. Whether you go one stop, or 5 stops, it is still good. The moment your switch systems, lines, or go a different direction, you need a new ticket. The interesting thing is that it is sort of the honor system – there are no turnstyles in the metro, and no one asking to see your tickets on the bus or the tram.
There is a catch – Should an official ask to see your ticket and you do not have validation, you pay a large fine (i’ve heard everything between 2500-7000 HUF).
While hungarian is a difficult language, reading the ticket seems to be a language in itself – I have no idea how the officials can interpret if your ticket is still valid or not.
I should share that from observation of the locals, they do not seem to buy/validate tickets for the bus or the tram, but the defenitely do on the metro.
I wrote this in Budapest, but after visiting Austria and Poland, I have learned that this sytem seems to be standard in all of these central european countries.