1. The possessive case of nouns is formed when we put “'s" to the noun.
Example: The girl's dress, the boy's pen.
2. The possessive case is used with the nouns of living things but not the inanimate objects.
Example: Table's leg (incorrect)
Leg of the table. (correct)
3. The possessive is used with the names of personified objects.
Example: Death's icy hands.
4. When the noun is plural, and ends in ‘s'; the possessive case is formed by adding only an apostrophe(after s)
Example: Girls' Hostel , Birds' Nest
5. When the noun is plural and does not end in a ‘s' , the possesinve case is formed by adding “'s"
Example: Men's club, Children's park
6. When the noun or a title consists of several words, the possessive case is formed by adding ‘s at the end of the last word.
Example: The Prime Minister of India's speech.
7. When two or more nouns are joined by ‘and', and a common possession is meant, the possessive case will be formed by adding ‘s to the last noun.
Example: Amar and Kumar's house is very beautiful. - The sentence denotes that the house belongs to both Amar and Kumar.
8. When there are two nouns in apposition , the possessive case will be formed by adding ‘s to the second noun.
Example: Penicillin, Flemming's discovery, has saved lives of many people.
9. The possessive case of a compound noun will be formed by adding ‘s to the last word.
Example : Sister-in-law's house.
10. If the last syllable of a singular noun ends in –s or –ce and the noun is followed by the word ‘sake' , the possessive case is formed by adding only the apostrophe at the end.
Example : for goodness' sake , for conscience' sake