LikhoPadho

The uses of Apostrophe are as follows :

1. It is used with the nouns to show possession 
For example 

1. The girl's dress
2. A women's handkerchief 
3. A boys' watch

2. When a noun ends with 's' or 'ss', an extra 's' is not added after the apostrophe 
For example

1. A  class' teacher
2. Jesus' disciples

3. An extra's is not added when the plural form of the nouns ends with 's' or 'es'
For example

1. Boys' school
2. Girls' bracelets

4. The letter 's' is added after the apostrophe when the plural forms of the nouns donot end with 's'
For example 

1. Men's job
2. Children's lady

5. Classical names ending in -s usually add only the apostrophe ['] 
For example

1. Pythagoras' Theorem
2. Moses' laws 

6. In compound Nouns, the last word takes the 's; 
For example

1. My sister-in-law's son
2. My mother-in-law's brother

7. The apostrophe will be used in the following manner in case of joint possession of two or more person.
For example

1. Gita and Sita's room.
2. Ram, Shyam and Ravi's father.

8. The apostrophe is used in contracted forms.
For example
 

I'am	didn't	won't
it's	they'd	they'll
can't	we'are	hasn't
we've	I'd	doesn't

9. Apostrophe is also used with nouns of space, time or weight 
For example

1. A month's salary
2. a pound's weight

10. A few common phrases use the 's; 
For example

1. at one's finger's ends
2. at one's wit's end