The Harmonized System
The Harmonized System is the international nomenclature customs authorities use to classify traded goods. The World Customs Organization maintains it and revises it every few years, and nearly every country's customs tariff is built on it.
It is read from the left, two digits at a time: the first two are the chapter, the first four the heading, and the first six the subheading. Those six are international.
Why the last digits differ
Beyond the six shared digits, each country or customs union adds its own. The European Union's Combined Nomenclature runs to eight digits and its TARIC import tariff to ten, and many other countries use ten as well. Those extra digits carry the duty rate and the national rules, so one product can share its first six digits everywhere and carry a different full code in each market.
Why it matters
The code decides the import duty and any licence, standard or labelling rule that applies at your border, and the commercial invoice is what your customs office assesses the duty on. A wrong code can mean the wrong duty, a delay, or a correction after the fact.
The importer is responsible for the code declared at import. That is why the code on a supplier's papers is a starting point to confirm with your customs broker or your customs authority, not a ruling.
Where to find a Lexical line's code
Each product page has an HS code row. A verified customer sees the full code there, with a Copy button, and on printed datasheets and the datasheet download; everyone else sees its first two digits, the chapter.
On a shipment, the commercial invoice lists the goods line by line, with HS codes where they are agreed in advance.