Cases

Russian nouns are declined: their endings change according to the case. There are six cases. Their principal meaning is summarized below: 

• The Nominative expresses the subject or predicate in answer to:   who? what? – кто? что?

• The Accusative expresses the direct object in answer to: whom? what? –  кого? что?

The other four cases are rendered into English with the aid of prepositions:  

• The Genitive answers the question: of whom? (whose?) of what? – кого? (чей?) чего?

• The Dative answers the question:   to whom? to what? – кому? чему?

• The Instrumental answers the question:  by whom? with  (by) what? –  кем? чем?

• The Prepositional answers the question: about whom? about what? where? – о ком? о чём? где?

The use of a case may also be determined by a preposition, a verb, or a special construction (such as an expression of time). This will be discussed in detail in the "Usage of Cases" chapter.