APOSTROPHE

Use an apostrophe and "s" to show possession for words that do not end
with the letter "s".

        Someone's ring was left on the sink. I used Mary's typewriter.

        Make the appointment with the doctor's secretary.

        It is against our company's policy to accept a resignation without formal notice.

Use an apostrophe to show possession for words that end with the letter "s".

        The National Teachers' Conference will be held in New Orleans.

        The government evaluates all companies' pension plans.

        Three doctors' reports were submitted for review.

Use an apostrophe to show that a number or numbers were omitted.

        the Spirit of '76 = the Spirit of 1776

        the graduating class of '77 = the graduating class of 1977

Use an apostrophe and "s" to show the plural of letters or figures.

        We sell more size 5's than any other size we stock.

        My handwriting is so sloppy everyone mistakes my i's for e's.

Use an apostrophe and "s" to indicate the possession of an abbreviated
word.

        I work in L.A.'s tallest building.

        You are requested to report to the D.A.'s office.

Use an apostrophe and "s" to show the plural of an abbreviated word.

        How many c.o.d's did you ship today?

        This section of the plane is reserved for VIP's only.

In informal letters, use an apostrophe to show that a letter or letters were
omitted.

        don't (do not)

        can't (cannot)

        doesn't (does not)

The contractions are used only in informal letters.