When is 's used?

Answer 1

It shows the possessive, such as: "the horses' mouth." ============================ Ooooh, I'm not so sure. An apostrophe is used to show the possessive, but the example is incorrect. When the apostrophe follows the letter 's' rather than preceding it, it indicates the plural as well as the possessive. The example above should read, "the horses' mouths," thus indicating that there is more than one horse and more than one horse's mouth. An apostrophe following the letter 's' is also frequently used to show the possessive when a word ends in the letter 's.' An example would be "Mr. Jones' hat." It avoids the somewhat awkward, but still correct, "Mr. Jones's hat." (Obviously, "Mr. Jone's hat" would be incorrect.)

Answer 2

When something belongs to something else: the book's cover, the girl's bag, the men's shoes. But when there is more than one girl: the girls' bags, the books' covers. It Is not used when you are counting: 3 books, 14 bags, a pair of shoes.

Answer 3

's can be used to indicate possession or a contraction. For example, "Lisa's book" shows possession, while "It's raining" is a contraction of "It is".