Apostrophe (’)

Punctuation: Apostrophe (’)   / Oxford Dictionary

• The apostrophe is used to form possessives of nouns : Add just an apostrophe to The end of plural nouns that end in -s and add  ‘s to the singular form of the word, to the plural forms that do not end in –s, to the end of compound words and to the last noun to show joint possession of an object.

                   The owners’ car

                   Uncle Sam’s hat

                   Chris’s game

• Apostrophes can also be used in contractions, to show the omission of letters.

                    It is = it’s

• you can use an apostrophe to show the plurals of single letters and numbers:

         The letter i’s and the number 7’s

• Don't use apostrophes for personal pronouns, the relative pronoun who, or for noun plurals.

                      INCORRECT: His’ book