Final answer:
Apostrophes are used to indicate possession and form contractions. Use an apostrophe and -s to show possession with a singular noun or indefinite pronoun. For plural nouns ending in -s, place the apostrophe after the final -s.
Step-by-step explanation:
Apostrophes are used to indicate possession and form contractions. When showing possession with a singular noun or indefinite pronoun, use an apostrophe and -s. For example, 'Jack's brother is my sister's coworker.' If the noun is plural and ends in -s, place the apostrophe after the final -s. For instance, 'American households' incomes have grown since the 1970s.' Contractions, on the other hand, combine two words by omitting one or more letters and replacing them with an apostrophe, such as 'won't' for 'will not' or 'can't' for 'cannot'.