Def: Case is the relation of a noun or a pronoun to the other parts of a sentence, or the form showing the relation.
Types: There are three principal cases in English:
i) Nominative Case: When noun or pronoun is the subject of the verb, then it is said to be in Nominative case.
Eg: Ram hits the ball.
I go to walk every morning.
** Nominative case or subject is the answer obtained by questioning the verb with 'what?' or 'who?'
ii) Objective Case: When noun or pronoun is the object to the verb or a preposition, then it is said to be in Objective case.
Eg: He wants his bat.
Rohit is hitting the dog.
** Objective case or object is the answer obtained by questioning the verb with 'what?' or 'whom?'
iii) Possessive Case: It denotes ownership or some other relation.
Eg: I am writing with Abhi's pen.
Raj is driving Rohan's car.