Courier services transport documents, packages, and shipments for clients. Shipping rates are influenced by commodity characteristics and classified based on density, handling, value, and damage susceptibility. Rates also vary by weight and exceptions are made for large volume shippers. Carriers offer all-commodity, value, deferred, and incentive rates. Couriers may encounter issues like getting lost, transporting fragile items, or vehicle breakdown but can mitigate these with GPS, proper packaging, and maintenance. Tariffs are taxes on imports/exports while customs agencies control trade flows and duties.