You almost always go through customs and immigration on arrival when entering a new country. The process is designed to vet people (Immigration/Passport Control) and goods (Customs) entering the sovereign territory. When you land, you first pass through immigration to verify your right to enter, then you collect your checked luggage, and finally, you pass through the "Customs" area where you declare items like tobacco, alcohol, large amounts of cash, or restricted food products. On departure, most countries do not have a formal "Customs" check for goods, though many do have Exit Immigration to record that you have left the country and haven't overstayed your visa. A notable exception is U.S. Preclearance, available at some airports in Canada, Ireland, the Caribbean, and the UAE; in these cases, you clear U.S. Customs and Immigration before you board your flight, meaning you arrive in the U.S. as a domestic passenger. Generally, however, the rule of thumb is: Immigration checks you, and Customs checks your "stuff," and both happens primarily when you first touch down in a foreign nation.