Hungary is a landlocked country and shares borders with Austria, Slovenia & Croatia to the west, Serbia & Romania to the south, with Ukraine to the east and Slovakia to the north.

Hungary is also a member of the European Union and the Schengen Area. European Union citizens have both the right to pass freely across Hungary's borders and have the right to settle, reside and work here. The Schengen Treaty promotes open borders, common travel visas and asylum rights across a vast swathe of continental Europe. If one country in the Schengen Area accepts you for entry, so do all the others. Non-EU citizens may, therefore, encounter tougher questioning when entering Hungary from a non-EU nation. 

Land border checkpoints have been abolished on the borders with Slovakia, Austria & Slovenia. Tight controls remain on the borders with Romania, Serbia & Ukraine, due to the suspected international drug trafficking rings importing to the EU via these nations.

Croatia, while not part of the Schengen Area, had a pre-Schengen agreement to allow its citizens to travel freely in Slovenia, Hungary and Italy using a national ID card. This arrangement is still in place, however, Croatian citizens do require entry and exit stamps (on an evidention card) from Hungary. If you are Croatian and planning trips to other Schengen nations, it is a requirement that you are in possession of a full passport.