Case is a grammatical category of nouns and words that function as nouns, reflecting different types of relationships between one substantive and another substantive, or a substantive and an action.

With the exception of the possessive case (see below ↓), in English, relationships between nouns in a sentence are expressed without changing the form of the word, only by means of prepositions. Also, the noun does not change its form depending on whether it is a subject or an object. Therefore, this form of the noun is distinguished as the common case:

• The child is looking at the child.

The main article: "Possessive Case".

A noun in the possessive case serves as a determiner of another noun and answers the question "whose?", denoting the relationship of belonging of one object to another. Nouns form the possessive case using the clitic -s, preceded by an apostrophe:

• the child's toy
• the airplane's crew

Unlike nouns and other pronouns, personal pronouns and the pronoun "who" change their form depending on whether they are the subject or object of a sentence:

• субъектный падеж или именительный падеж (subjective case / nominative case)
  1. I am looking at the child. – Я смотрю на ребёнка.
  2. Who is looking at the child? – Кто смотрит на ребёнка?
• объектный падеж или косвенный падеж (objective case / accusative case):
  1. The child is looking at me. – Ребёнок смотрит на меня.
  2. Whom is the child looking at? – На кого смотрит ребёнок?

The use of the term "common case" in relation to pronouns that have different forms for the subject and for the object is inappropriate.

The possessive case of personal pronouns is not formed in a regular way and they just need to be memorized:

• his toy;
• her voice.

The vocative case has no morphological features and is no different in form from the common case; it is sometimes distinguished based on its semantic role - it names the object to which the address is directed. In writing, a noun in the vocative case is separated by a comma:

• Nelly, what are you watching?
• Where have you been, Charlie?

Obsolete, as well as in poetic and rhetorical speech, the vocative phrase in English was preceded by the word "O":^[1]

• O ye of little faith^[2];
• O Best Beloved^[3].