Kaliningrad
In short
A Russian city and the administrative centre of the Kaliningrad Oblast. It is a unique exclave located between Poland and Lithuania on the Baltic Sea.
In plain words
It is a piece of Russia that is not connected to the rest of the country. It sits on the coast and serves as an important port that does not freeze in winter.
A simple example
If you travel from Moscow to Kaliningrad by land, you must pass through other countries like Belarus or Lithuania.
Why it matters
Its location makes it a key strategic point for Russia in Europe. It provides a vital ice-free maritime gateway for the Russian navy and trade.
Easy to mix up
Do not confuse it with Königsberg, which was its former name before 1946.