The Easternmost region of Europe. If you ask a Czech or a Pole, The Czech Republic, Poland, Hungary, and Slovakia are a part of Central Europe, not Eastern Europe. If you ask anyone else, The Czech Republic, Poland, Hungary, and Slovakia are a part of Eastern Europe, not Central Europe. This is a common source of strife in Off-Topic, although many see it as a joke. This does not have much effect on DYOS, although it has provided some jokes sometimes.
During the Cold War, the Soviet Union made a politically-charged point of referring to itself and its satellite states as constituting "Eastern Europe", to distinguish the Workers' Paradise from the corrupt, exploitative, oppressive capitalist hell-hole to the west. After the breakup of the USSR in 1991, the liberated nations were quick to reject the term, forcing universities the world over to rename the "Department of Soviet and Eastern European Affairs" to the much more succinct "Department of Central Eastern European Regional Studies", or something like that.