Why does Polish use letter combinations such as sz to represent Slavic sounds?

Polish uses letter combinations like sz because the Latin alphabet was not originally designed to represent the specific phonemes found in Slavic languages. When adapting the Latin script to Polish, writers faced the challenge of representing sounds that did not exist in the languages for which the alphabet was originally intended.12

To bridge this gap, Polish adopted a system of combining multiple letters to represent these unique sounds, such as using sz for the "sh" sound. This approach differs from other Slavic writing systems, such as Czech, which primarily utilized diacritical marks to distinguish sounds. While Czech orthography was later reformed by Jan Hus to standardize the use of diacritics, Polish spelling remained patterned after the pre-Hus Czech orthography of the 14th century, which relied more heavily on these letter combinations.12