A courier is a person or a company who delivers messages, packages, and mail. 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 usual mail services, and their use is typically restricted to packages where one or more of these features are considered important enough to warrant the cost.

Different courier services operate on all scales, from within specific towns or cities, to regional, national and global services. The world's largest courier companies are DHL, FedEx, TNT, UPS, and Aramex. These offer services worldwide, typically via a hub and spoke model.

You have probably seen the very visible couriers around towns and cities these days, sometimes on motorbikes, but mainly in vans. Many people confuse same day couriers with overnight couriers such as DHL and UPS, these are in fact completely different industries using completely different methods to deliver parcels around the country. An overnight company uses large fleets of vehicles delivering up to 70 packages each per day, combined with large warehouse facilities and large amounts of staff.

A same day courier is someone who will collect your consignment immediately anywhere in the U.K. whatever the time of day and deliver it to its destination in the fastest time possible.