To announce means to make something known publicly or officially. When the principal announces over the loudspeaker that school will end early due to snow, she's telling everyone important information they need to know. When a company announces a new product, they're formally revealing it to the world.

The word carries a sense of importance and formality. You wouldn't announce that you're going to sharpen your pencil, but you might announce the winner of a contest or announce your decision about which high school you'll attend. News anchors announce breaking stories. Referees announce penalties. Wedding guests wait eagerly for someone to announce that dinner is served.

An announcement is the actual statement being made. Saying “I have an announcement to make” means you're about to share news. When someone describes themselves as an announcer, they're usually a professional who shares information publicly, like a sports announcer who describes the action during a baseball game or a train station announcer who tells passengers which platform their train will arrive at.

The word suggests you're not just mentioning something casually. You're making sure people hear it and understand that it matters.