Russian is an inflective language. It means that the word in a sentence takes different endings depending on a role of this word in the sentence. The roles of the words in Russian are expressed by the cases. English, unlike Russian, is analytic language, and the role of words is expressed by prepositions, postpositions and the strict word order. I will give you a detailed example:
In English we say Mary sees the guy.
Let’s translate each word in Russian:
Mary – Маша (I have adapted the name Mary to its Russian version)
to see – видеть
guy – парень
In Russian we say Маша видит парня.
In the sentence, two words have changed their initial form: the verb видеть and the noun парень. I will talk about verb conjugations in our next lesson.
The noun Маша in this sentence is a subject (an actor), that’s why it stayed in its initial form (nominative case). The noun парень is an object of an action, that’s why it took form of the accusative case: парня.
If we change the word order in English, we will get: The guy sees Mary.
Now it’s Mary who is the object of an action.
Now let’s change the word order in the Russian sentence: Парня видит Маша.
The noun guy is still the object because it is in accusative case. If we want to say that it is the guy who sees Mary, we should say:
Парень видит Машу.
Here, Парень is in nominative case, and Маша is in accusative case.
As you can see from this example, it is the case of a noun that determines its role in a sentence. There are six cases in Russian: nominative, genitive, dative, accusative, instrumental, and prepositional. Let’s look how the noun парень changes by cases. In this word, we drop the e and add the ending of the cases to the stem парн:
The nominative case. It is the subject of a sentence. The noun stays in its initial form:
Парень читает книгу. – The guy is reading a book.
This is also the dictionary form of the noun so when you see a noun in the vocabulary it is generally in the nominative case unless otherwise specified.
The genitive case. It is used to show the possession or reference. It can be expressed by the preposition of:
Книга парня. – The guy’s book (The book of the guy).
It also may mean an absence of something or somebody:
Парня здесь нет. – The guy isn’t there.
The dative case is used when something is given or adressed to the noun:
Идти к парню. – To go to the guy.
Дать книгу парню. – To give the book to the guy.
The accusative case is the object of a sentence:
Я знаю этого парня. – I know this guy.
The instrumental case indicates several meanings: it can be an instument that helps to do something or it also can follow the conjunction с (with):
Дом построен парнем. – The house is built by the guy.
Она ушла с парнем. – She left with the guy.
The prepositional case designates something (somebody) that (who) is an object of speech or thoughts:
Она говорит о парне. – She is talking about the guy.
It also means a place (location) of something (somebody):
Куртка на парне. – The jacket is on the guy.
Keep in mind that not all nouns have the same endings as the noun парень. The ending in each case depends on the gender and number of the noun. For example, the scheme above is only applicable to nouns of the second declension. You will learn more about declensions in our lesson 5.
To see endings of nouns of all declensions in all cases, check this grammar lesson.