what does usps priority mail mean refers to a service offered by the United States Postal Service (USPS) that provides fast and reliable delivery for parcels and letters. Priority Mail is typically delivered within 1-3 business days, depending on the destination. This service is often used for packages that are time-sensitive but not as urgent as overnight services. Priority Mail includes tracking, and the option for flat-rate shipping allows for predictable pricing based on the size of the package, regardless of weight, within certain limits.