At the border travelers declare goods they are bringing into the country and may have luggage inspected for prohibited or dutiable items. That control function is customs. It protects revenue, safety, and agricultural health.

Duty-free allowances set limits on alcohol, tobacco, and other goods. Prohibited items typically include certain foods, weapons, and counterfeit products. Green and red channels separate travelers with nothing to declare from those who must speak with an officer. Random and targeted inspections occur in both.

Accurate declaration avoids penalties. Commercial shipments face more complex procedures than personal luggage. For most tourists customs is a brief final step before exiting the airport; for others it becomes a detailed examination. Knowing the rules of the destination prevents most problems.

The customs channel is the last formal barrier between the flight and the destination itself.