punctuation: apostrophe

We use apostrophes (‘) in two important ways.

    a. To show where we have left letters out of a contracted form.
    can’t ( = cannot) she’s ( = she Is) I’d ( = I would)
    b. In possessive forms of nouns.
    the girl’s father Charles’s wife three miles’ walk

We do not use apostrophes in plurals, possessive determiners (except one’s) or possessive pronouns.

    blue jeans (NOT blue jean’s)
    The dog wagged its tail (NOT . . . H’s tatb)
    This is yours. (NOT . . . your’s.)