Concern means to worry about something or to be about something. When your parents express concern about your grades, they're worried and want to help you improve. When a story concerns a brave explorer, it's about that explorer's adventures.

The word carries a sense of caring or involvement. If something concerns you, it matters to you personally. A teacher might say, “This concerns all of you,” when announcing something the whole class needs to know. Scientists express concern about endangered species because they care about protecting wildlife. A friend might ask, “What's your concern?” when you seem troubled about something.

Concern can also be a noun meaning the worry itself. You might have concerns about an upcoming performance, or your coach might address the team's concerns before a big game. A business is sometimes called a going concern, meaning a working company.

People sometimes confuse concern with related words. Worry suggests more anxiety and distress, while concern can be calmer and more thoughtful. You might be concerned about littering and take action to keep your community clean, while worry might just keep you up at night. When something is of no concern to you, it doesn't affect you, or you're choosing not to let it bother you.