In the Czech Republic two distinct variants or interdialects of spoken Czech can be found, both corresponding more or less to geographic areas within the country. The first, and most widely used, is "Common Czech", spoken especially in Bohemia. It has some grammatical differences from "standard" Czech, along with some differences in pronunciation. The most common pronunciation changes include -ý becoming -ej in some circumstances, -é becoming -ý- in some circumstances (-ej- in others). Also, noun declension is changed, most notably the instrumental case. Instead of having various endings (depending on gender) in the instrumental, Bohemians will just put -ama or -ma at the end of all plural instrumental declensions. Currently, these forms are very common throughout the entire Czech republic, including Moravia and Silesia. Also pronunciation changes slightly, as the Bohemians tend to have more open vowels than Moravians. This is said to be especially prevalent among people from Prague.
The second major variant is spoken in Moravia and Silesia. Nowadays it is very close to the Bohemian form of Common Czech. This variant has some words different from its standard Czech equivalents. For example in Brno, tramvaj (streetcar or tram) is šalina (originating from German "ElektriSCHELINIE"). Unlike in Bohemia, Moravia and Silesia tend to have more local dialects varying from place to place, however just as in Bohemia, most have been already heavily influenced and mostly replaced by Common Czech. Everyday spoken form in Moravia and Silesia would be a mixture of remnants of old local dialect, some Standard Czech forms and especially Common Czech. The most notable difference is a shift in used prepositions and case of noun, for example k jídlu (to eat - dative) (as in German zum Essen) becomes na jídlo (accusative), as it is in Slovak na jedlo. It is a common misconception that the use of Standard Czech in everyday situations is more frequent than in Bohemia. The Standard Czech became de-facto standardized with a new translation of the Bible (Bible of Kralice) using an older variant of the then-current language (for example, preferring -ý- to -ej-). These Standard forms are still common in spoken language both in Moravia and Silesia. Some Moravians and Silesians therefore tend to say that they use "proper" language, unlike their Bohemian compatriots.Free quote
A special case is the Cieszyn Silesian dialect, spoken in the microregion of Cieszyn Silesia. It is spoken generally by the ethnic Polish minority. The dialect itself is a dialect of Polish but with strong Czech and German influences.
It should be noted that some south Moravian dialects are considered (also by Czech linguists in the 90's or later, e.g. Václav Machek in his "Etymologický slovník jazyka českého", 1997, ISBN 80-7106-242-1, p.8, who speaks about a "Moravian-Slovak" dialect from the region of Moravian "Slovácko") to be actually dialects of the Slovak language, which has its roots in the Moravian empire when Slovaks and Moravians were one nation (without Bohemians) with one language. Those dialects still have the same suffixes (for inflected substantives and pronouns and for conjugated verbs) as Slovak.
The minor dialect spoken in Pilsen and parts of Western Bohemia differs, among other things, by intonation of questions: all the words except for the last word of a sentence have a high pitch. This is the reason why the people from Pilsen are said to be "singing". Words that start questions are often given an additional "pa": "Kolipa je hodin?" (regular Czech: "Kolik je hodin?"; English: "What time is it?"). The words like "this" (regular Czech: "tento/tato/toto") are often replaced by "tuten/tuta/tuto").