priority mailing is a USPS service that allows customers to send packages and letters with faster delivery times, typically within 1-3 business days, depending on the destination. Priority Mail is available for both domestic and international shipments and comes with several benefits, such as tracking, insurance (for up to $50), and delivery updates. USPS also offers flat-rate shipping options, where the shipping cost remains the same regardless of the weight of the package (as long as it fits within the specified flat-rate box or envelope). This service is ideal for sending time-sensitive packages and offers a balance of speed and cost for businesses and individuals.