1. Possession:
* Singular noun: The cat's tail is fluffy. (The tail belongs to one cat)
* Plural noun ending in "s": The cats' tails are fluffy. (The tails belong to multiple cats)
* Plural noun not ending in "s": The children's toys are scattered. (The toys belong to the children)
2. Contractions:
* Combining words: I'm going to the store. (I am)
* Leaving out letters: Don't forget your homework. (Do not)
* Special cases: It's a beautiful day. (It is) They're going to the beach. (They are)
3. Plurals of letters and numbers:
* Letters: There are three A's in the word "banana."
* Numbers: He scored two 10's on the test.
More examples:
* It's a shame you missed the party. (It is)
* Who's coming to the party? (Who is)
* He's been studying all night. (He has)
* Let's go to the movies. (Let us)
* That's my favorite book. (That is)
* They've already left. (They have)
* She'd like to go, but she can't. (She would)
* The dog's bone is missing. (The bone belongs to the dog)
* My parents' car is parked in the driveway. (The car belongs to my parents)
Important Note:
Apostrophes are often misused. Be careful not to use them in place of plural "s."
* Incorrect: The students went to the store to buy apples.
* Correct: The students went to the store to buy apples.
Let me know if you have any other questions about apostrophes!