The term customer is c. 1200, custume, "habitual practice," either of an individual or a nation or community, from Old French costume "custom, habit, practice; clothes, dress" (12c., Modern French coutume), from Vulgar Latin *consuetumen, from Latin consuetudinem (nominative consuetudo) "habit, usage, way, practice, tradition, familiarity," from consuetus, past participle of consuescere "accustom." Customs in international trade is by 1921.

Customs is a government authority designated to regulate flow of goods to/from a country and to collect duties levied by a country on imports and exports. The term also applies to the procedures involved in such activities. Traditionally, customs representation could only be carried out by customs brokers who had to take a public examination. Currently, customs representation can also be carried out by forwarders and companies with a customs domiciliation.

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Customary state, practice in impermanence, costumes of nature