The Czech language belongs to West Slavic languages, within the Indo-European group of languages, together with Polish and Slovak. The Czech and Slovak languages are very close and mutually intelligible. The phonology of Czech may also be very difficult for speakers of other languages. For example, some words do not appear to have vowels. Many Czechs, especially in the larger cities, speak good English and it is possible to get by in the Czech Republic without mastering Czech, although it can be recommended to make the effort to learn the language if residing there for a longer period.