A declaration is a formal announcement or statement, especially one that makes something official or publicly known. When the American colonies issued the Declaration of Independence in 1776, they weren't just complaining about British rule: they were formally announcing to the world that they were now a separate, independent nation. That declaration changed history because it turned private grievances into a public, official position.

You make declarations in everyday life too, though usually less dramatic ones. When you declare that you're going to read fifty books this year, you're announcing your intention clearly and firmly. When a teacher declares that homework is due Friday, she's making an official statement everyone needs to follow. In court, witnesses must declare that they'll tell the truth.

The word carries weight and seriousness. You wouldn't say “I declare I want a snack” because that sounds too formal. But you might declare your candidacy for student council president, or declare a major in college, because those are significant choices you're making official.

A declaration differs from a casual comment because it's purposeful and often public. When you declare something, you're taking a stand and making it known.