"Priority mail" refers to a type of postal service that ensures faster delivery of packages or letters compared to regular mail. It is given higher importance or priority in terms of transportation and processing. Full definition
* All 12 items to be mailed to you will be packaged in our special bag, and quickly sent out to you via priority mail. (medicalbillinglive.com)
However if you would like your certificate sent by priority mail or next day delivery we have those those options available as well. (nostresstrafficschool.com)