This document discusses the proper use of apostrophes to show possession and contractions. It explains that apostrophes are used to show missing letters in contractions and to indicate possession or ownership. For singular possessive nouns, an apostrophe-s is added. For plural nouns ending in s, only an apostrophe is added. For plural nouns not ending in s, an apostrophe-s is added. Compound nouns showing joint possession take an apostrophe-s after the second noun only, while individual possession uses a double possessive.