A reference is a mention of something or someone that helps explain, support, or connect to what you're talking about. When you write a report about dolphins and include a reference to a book you read, you're pointing readers to where you found your information. When a teacher makes a reference to a story the class read last month, she's bringing up that story to help explain today's lesson.

References work like signposts. If you're discussing basketball and make a reference to Michael Jordan, you're connecting your point to someone your audience likely knows. If you're arguing that your school needs longer recess and you reference a study showing that exercise helps kids focus, you're using that study to strengthen your argument.

The word also describes a letter or a person who can vouch for your character or abilities. When applying for a summer program, you might ask a teacher to serve as a reference: someone who knows you well and can tell the program organizers about your strengths and reliability.

In libraries and research, a reference book like an encyclopedia or dictionary is designed for looking up specific information rather than reading cover to cover. These books help you find facts quickly when you need them.