When something expires, it reaches the end of its valid or usable period. Your library card might expire after a year, meaning you need to renew it before you can check out more books. A carton of milk expires when it's no longer safe to drink. A coupon expires when the date passes and stores won't accept it anymore.

In rare literary contexts, expire can mean to die, though this usage sounds old-fashioned today. When we talk about things expiring in everyday life, we mean they've reached their deadline or their time limit has run out.

You'll see expiration dates on food packaging, showing when something should be used for safety or freshness. Subscriptions expire: your family's streaming service might expire if you don't renew it. Parking meters expire when your time runs out. Even opportunities can expire: if you don't sign up for summer camp by Friday, your chance to register might expire.

Expired is the past tense, describing something that's already run out: an expired password, an expired permit, or expired medicine that should be thrown away. Understanding when things expire helps you stay organized and safe.