This document discusses possessives and how to form them according to three rules. Rule 1 states that to make a singular noun possessive, add 's. Rule 2 says that for plural nouns ending in s, just add an apostrophe. Rule 3 explains that for plural nouns not ending in s, add 's. It provides examples for each rule to demonstrate how to indicate something belongs to or is possessed by a noun. The document emphasizes that possessives show ownership or that something belongs to someone or something.