Question: what are apostrophes used for?
Answer: The apostrophe has three uses: 1) to form possessive nouns; 2) to show the omission of letters; and 3) to indicate plurals of letters, numbers, and symbols. ​Do not ​use apostrophes to form possessive ​pronouns ​(i.e. ​his​/​her ​computer) or ​noun ​plurals that are not possessives.