Kashubian - depending on opinion is a dialect of Polish language or a separate West Slavic language. It is spoken by about 50.000 people, called Kashubians, who live in the Pomerania, a region situated in the north of Poland.
Belonging to the so called Lechitic family of Slavic languages it shares its feautures with Polish and Polabian languages. The centuries of mutual integrity of Pomerania and central Poland have made Kashubian closer to the adiacent Polish dialects - Mazovian and Lesser Polish. With the first it shares the alteration of a into e vowels in such particles as ra-, ja- and -ar-. With the second one, Kashubian shares lack of Mazurzenie, so cz, dż and sz digraphs do exist as well as ż sound. However, probably because of a strong germanic influence, Kasubian lost a similar set of consonants: ć, dź, ś and ź for the benefit of c, dz, s and z. This process is called Kaszubienie in Polish dialectology.
With Polabian Kashubian has TarT and TłoT forms in common. However, because of the strong influence of standard Polish this feature tends to disappear.
In 2005, after Polish parliament had enacted the law about ethnical and national minorities and regional languages, Kashubian was granted an official status as a regional language. This became the strongest argument of Kashubian separateness supporters to treat it as a fully-fledged Slavic language. Traditionalists still prefer to classify Kashubian as one of the Polish dialects, though.