An acquaintance is someone you know, but not very well. They're more than a complete stranger but less than a friend. You might recognize an acquaintance's face, know their name, and say hello when you see them, but you probably wouldn't invite them to your birthday party or tell them your secrets.

Think of the kids in your grade you see in the hallways or at lunch. Some are close friends you hang out with after school. Others are acquaintances: you know who they are, maybe you've worked together on a project or two, but you don't really spend time together outside of school. Your parents' coworkers, your neighbors down the street, or the librarian who helps you find books are likely acquaintances rather than friends.

The difference matters because we treat acquaintances differently than friends. You might tell a friend you're worried about an upcoming test, but you'd probably just make polite small talk with an acquaintance. Many acquaintances stay acquaintances forever, but some become friends over time as you get to know them better.