A courier is a person who delivers messages, packages, and mail.
Duties and functions
Couriers are distinguished from ordinary mail services by features such as speed, security, tracking, signature, specialization and individualization of express services, and swift delivery times, which are optional for most everyday mail services. As a premium service, couriers are usually more expensive than standard mail services, and their use is normally limited to packages where one or more of these features are considered important enough to warrant the cost.
Courier services operate on all scales, from within specific towns or cities, to regional, national and global services. Large courier companies include DHL, OCS, FedEx, DTDC, EMS International, TNT, UPS, and Aramex. These offer services worldwide, typically via a hub and spoke model.
Before the industrial era
In ancient history, runners and homing pigeons and riders on horseback were used to deliver timely messages. Before there were mechanized courier services, foot messengers physically ran miles to their destinations. To this day, there are marathons directly related to actual historical messenger routes. In the Middle Ages, royal courts maintained their own messengers who were paid little more than common labourers.