The Harmonized System gave every traded good one code every customs can read

Goods move across borders, but the way countries described them did not. Every customs administration built its own tariff nomenclature, so the same object could be called, counted and taxed differently at each frontier, and trade statistics could not be compared at all.

The World Customs Organization developed the Harmonized Commodity Description and Coding System, known as the Harmonized System or HS — a nomenclature of transportable goods that became a universal language for identifying and coding merchandise traded internationally. Its structure assigns each product a six-digit code.

The WCO drew up the international convention on the HS and the codes entered force on 1 January 1988. Since then almost every economy has used the HS as the basis of its customs tariffs and the collection of trade statistics, and it is revised on a five-year cycle to reflect changes in technology and patterns of trade.

The result is that two countries refer to a product by the same code, so tariffs, rules of origin, trade data and disputes can all share a single reference rather than a translation table. A classification is no longer a local opinion.