Adapted from Wikipedia
The polka is a lively Central European dance and also a genre of dance music familiar throughout Europe and the Americas. It originated in the middle of the 19th century in the Czech lands and is still a common genre in Lithuanian, Czech, Croatian, Slovenian, Polish, German, Hungarian, Austrian, Ukrainian, Belarusian, Russian, and Slovakian folk music. Versions are also found in the Nordic countries, Ireland and Latin America, especially Mexico.
The name comes from the Czech word půlka - literally little half - a reference to the short half-steps featuring in the dance. The word's familiar form has been influenced by the similarity to the Czech word polka, meaning "Polish woman". The name has led to the dance's origin being sometimes mistakenly attributed to Poland. It should also not be confused with the polska, a Swedish 3/4-beat (help·info) dance with Polish roots; cf. polka-mazurka. A related dance is the redowa. Polkas almost always have a 2/4 [Time Signature].