Use an apostrophe to show contractions. “They’re on vacation and can’t get back in time for the meeting.”

Use an apostrophe to show plural of lower case letters. “I made sure that I dotted all my i’s and crossed all my t’s before I signed the contract.”

Use an apostrophe to show possession in a single compound noun. “We are living in my mother-in-law’s house until ours is finished.”

Use an apostrophe to form the possessive case of indefinite pronouns. “This election could be anyone’s win.”

Use an apostrophe in expressions of time or value: two weeks’ notice, two dollars’ worth of nuts.