Czech (čeština, historically also Bohemian; lingua Bohemica in Latin), is a West Slavic language of the Czech–Slovak group, that is strongly influenced by Latin and German. It is spoken by over 10 million people and is the official language of the Czech Republic. Czech is closely related to Slovak, to the point of being mutually intelligible to a very high degree.

The Czech-Slovak group developed within West Slavic in the high medieval period, and the standardisation of Czech and Slovak within the Czech–Slovak dialect continuum emerges in the early modern period. In the later 18th to mid-19th century, the modern written standard was codified in the context of the Czech National Revival. The main vernacular, known as Common Czech, is based on the vernacular of Prague, but is now spoken throughout most of the Czech Republic. The Moravian dialects spoken in the eastern part of the country are mostly also counted as Czech, although some of their eastern variants are closer to Slovak.

The Czech phoneme inventory is moderate in size, comprising five vowels (each short or long) and twenty-five consonants (divided into "hard", "neutral" and "soft" categories). Words may contain uncommon (or complicated) consonant clusters, including one consonant represented by the grapheme ř, or lack vowels altogether. Czech orthography is simple, and has been used as a model by phonologists.