International shipments require customs documentation, including commercial invoices, packing lists, certificates of origin, and customs declarations. These documents verify the shipment's legality, origin, and classification for taxation and import control purposes. CLT 4.0 highlights customs paperwork as essential for clearance through border control, preventing delays and ensuring compliance with import/export laws. The U.S. Customs and Border Protection (CBP) uses these documents to assess duties and inspect shipments. Failing to include accurate customs documentation can result in fines, detention, or refusal of entry. While a commercial invoice is one part of this process, customs documentation encompasses all required regulatory paperwork used for both import and export control.