differences are minor. Central Slovak forms the basis of the present-day standard language. Not all dialects are fully mutually intelligible. It may be difficult for an inhabitant of the western Slovakia to understand a dialect from eastern Slovakia and the other way around.
The dialects are fragmented geographically, separated by numerous mountain ranges. The first three groups already existed in the 10th century. All of them are spoken by the Slovaks outside Slovakia, and central and western dialects form the basis of the lowland dialects (see above).
The western dialects contain features common with the Moravian dialects in the Czech Republic, the southern central dialects contain a few features common with South Slavic languages, and the eastern dialects a few features common with Polish and the East Slavonic languages (cf. Štolc, 1994). Lowland dialects share some words and areal features with the languages surrounding them (Serbo-Croatian, Hungarian, and Romanian).
Standard Slovak (spisovná slovenčina) is defined by an Act of Parliament on the State Language of the Slovak Republic (language law). According to this law, Ministry of Culture approves and publishes the codified form of Slovak based on the judgment of specialised Slovak linguistic institutes and specialists in the area of the state language. This is traditionally Ľudovit Štúr Institute of Linguistics, which is part of the Slovak Academy of Sciences. In practice, Ministry of Culture publishes a document that specifies authoritative reference books for standard Slovak usage, which is called 'kodifikačná príručka' (codification handbook). Current regulation was published on 15 March 2021. There are four such publications:
The following languages have been given special protection under the European Charter [in Hungary]: Armenian, Beas, Bulgarian, Croatian, German, Greek, Polish, Romani, Romanian, Ruthenian, Serbian, Slovak, Slovenian and Ukrainian.