A customs area is an area designated for storage of commercial goods that have not yet cleared customs

Customs

Customs is an authority or agency in a country responsible for collecting and safeguarding customs duties and for controlling the flow of goods including animals, transports, personal effects and hazardous items in and out of a country...

. It is surrounded by a customs border. Most international airports and harbours have designated customs areas, sometimes covering the whole facility and including extensive storage warehouse

Warehouse

A warehouse is a commercial building for storage of goods. Warehouses are used by manufacturers, importers, exporters, wholesalers, transport businesses, customs, etc. They are usually large plain buildings in industrial areas of cities and towns. They usually have loading docks to load and unload...

s.

While territorially part of the country of the customs authorities, goods within the customs area have not technically entered the country yet, and may later be subject to customs duties. The goods within the area are also subject to checks regarding their compliance with local rules (for example drug laws and biosecurity

Biosecurity

Biosecurity is a set of preventive measures designed to reduce the risk of transmission of infectious diseases, quarantined pests, invasive alien species, living modified organisms...

 regulations), and thus may be impounded

Search and seizure

Search and seizure is a legal procedure used in many civil law and common law legal systems whereby police or other authorities and their agents, who suspect that a crime has been committed, do a search of a person's property and confiscate any relevant evidence to the crime.Some countries have...

 or turned back. For this reason, the customs areas are usually carefully controlled and fenced.

The fact that goods are technically still outside the country of the customs area also allows easy transshipment

Transshipment

Transshipment or Transhipment is the shipment of goods or containers to an intermediate destination, and then from there to yet another destination....

 to a third country without the need for customs checks or duties.

Other uses

The term is also sometimes used to define an area (usually composed of several countries) which form a customs union

Customs union

A customs union is a type of trade bloc which is composed of a free trade area with a common external tariff. The participant countries set up common external trade policy, but in some cases they use different import quotas...

, or to describe the area at airports and ports where travellers are checked through customs.