A courier is a person or company employe to deliver messages, packages and mail. Couriers are distinguished from ordinary mail services by features such as speed, security, tracking, signature, specialization and individualization of services, and committed 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.