There are three uses for the apostrophe:           
                                                       

		to show possession
		to show omission
		to show certain plurals of lowercase letters

Show Possession

To show something that belongs to someone. Add an apostrophe "s" to show possesion.

   Karl's car

   Mike's ball

   children's toys

To show omission meaning to take the place of a missing letter such as:

   that's= that is

   can't= cannot

   what's= what is

To show plurals of letters

To form plurals of letters that appear in lowercase:

   Cross your t's and dot your i's

   Since that boy lost his tongue he had problem pronouncing his the's

   Do you know how to say your q's