Passport renewal is the process of updating an expired or soon-to-expire passport. This is necessary to ensure that you can travel internationally without issues. Typically, you can renew your passport by mail if it meets certain criteria, such as being undamaged and issued when you were an adult. To begin the renewal process, you need to fill out the appropriate form, usually Form DS-82 for mail-in renewals. You will also need to provide a recent passport photo, pay the renewal fee, and send your old passport along with the application. Processing times can vary, so it's best to apply well in advance of any planned travel.