The Slovak language is the official language of the Slovak Republic. Slovak is spoken by 4.5 million inhabitants of Slovakia, more than one million emigrants in the United States, and approximately 300,000 people in the Czech Republic. Smaller Slovak-language communities are situated in Hungary, Romania, Serbia, Croatia, Bulgaria, Poland, France, Germany, Belgium, Austria, Norway, Denmark, Finland, Sweden, Italy, Switzerland, Netherlands, Cyprus, Russia, Ukraine, Kyrgyzstan, Israel, Canada, South Africa, Argentina, Brazil, Uruguay, Australia, New Zealand, United Kingdom, and other countries. Slovak is known as the "Esperanto" of Slavic languages, because it is regarded as the most comprehensible language for the speakers of other Slavic languages.
Although Slovak and Czech evolved separately and independently for a long period (Slovakia became a part of the Kingdom of Hungary in the 11th century), they remained similar to one other. However, some specific features of the Slovak language (the forms of lakeť, Česi, the suffix -m in the first person singular, etc.) are paralleled in South Slavic languages. In older Slavonic studies, they were incorrectly designated as South Slavisms in (central) Slovak. Some less significant aspects of Slovak resemble Polish (prefix pre-, unlike the Czech pro; preservation of the consonant dz, and several expressions such as teraz, pivnica).
In other characteristics, it resembles East Slavic languages. Therefore, it makes sense to speak about the "central" position of Slovak among the Slavic languages.
In the Indo-European family of languages, Slovak belongs to the Western branch of Slavic languages, together with Polish, Czech, and Lower and Upper Sorbian. Linguistic, historic, and archaeological sources prove that Slovak developed directly from Proto-Slavic (without passing through a Proto-Czechoslovak stage of development). The Proto-Slavic base of the Slovak language developed in the region between the Carpathians, the Danube, and the Upper Morava. This region was in contact with the West Slavic area to the west and with the East Slavic area to the north and north-east.