Russian has six grammatical cases called 'padezhi'. These cases determine how words change their endings depending on their function in a sentence. The six cases are: Nominative, which is the basic dictionary form; Genitive, which often shows possession; Dative, which indicates to whom something is given; Accusative, which shows the direct object; Instrumental, which shows by what means an action is done; and Prepositional, which is always used with prepositions. Understanding these cases is essential for speaking Russian correctly.
Let's look at the first two cases in detail. The Nominative case, or Imenitelny padezh, is the basic form of a word. It's used for the subject of a sentence and answers the questions 'Who?' or 'What?'. For example, in the sentence 'Книга лежит на столе', meaning 'The book is lying on the table', 'книга' is in the nominative case. The Genitive case, or Roditelny padezh, often shows possession, absence, or quantity. It answers the questions 'Whom?' or 'What?' in the sense of 'of whom' or 'of what'. For example, in 'Это дом моего друга', meaning 'This is my friend's house', 'моего друга' is in the genitive case. Notice how the word endings change between cases.
Now let's examine the Dative and Accusative cases. The Dative case, or Datelny padezh, is used for the indirect object - the person or thing to whom something is given or for whom something is done. It answers the questions 'To whom?' or 'To what?'. For example, in 'Я дал книгу сестре', meaning 'I gave the book to my sister', 'сестре' is in the dative case. The Accusative case, or Vinitelny padezh, is used for the direct object - the person or thing directly affected by the action of the verb. It answers the questions 'Whom?' or 'What?'. In our example sentence, 'книгу' is in the accusative case. Notice how in Russian, the word endings change to show these different grammatical relationships.
Let's complete our overview with the final two cases. The Instrumental case, or Tvoritelniy padezh, indicates the instrument or means by which an action is performed. It answers the questions 'By whom?' or 'By what?'. For example, in 'Я пишу ручкой', meaning 'I write with a pen', 'ручкой' is in the instrumental case. The Prepositional case, or Predlozhniy padezh, is always used with a preposition and typically indicates location or the topic of discussion. It answers the questions 'About whom?', 'About what?', or 'Where?'. In 'Книга лежит на столе', meaning 'The book is lying on the table', 'столе' is in the prepositional case. Notice that the word 'книге' in the prepositional case has the same form as in the dative case, but it's used with different prepositions and in different contexts.
To summarize what we've learned about Russian cases: Russian has six grammatical cases that change word endings based on their function in a sentence. The Nominative case is used for the subject, the Genitive for possession, the Dative for indirect objects, the Accusative for direct objects, the Instrumental for means or accompaniment, and the Prepositional for location or topics of discussion. These cases are indicated by changing the endings of words, as we saw with our example word 'книга'. Understanding these cases and how they transform words is essential for speaking and writing Russian correctly. While it may seem complex at first, with practice, the pattern of case endings becomes more intuitive.