You may assume that every member of your inner circle knows one another, but that’s not always the case. “When you fail to introduce everyone in your party, it doesn’t make each person feel valued and it also sends a message to the other person that they aren’t worth knowing,” says Toni Dupree, founder of Etiquette And Style By Dupree, a Houston-based etiquette and finishing school. “When in doubt, always play it safe and introduce people who might not know each other to avoid making anyone feel left out.”