The Harmonized Commodity Description and Coding System generally referred to as "Harmonized System" or simply "HS" is a multipurpose international product nomenclature developed by the World Customs Organization (WCO).
The HS is thus a universal economic language and code for goods, and an indispensable tool for international trade. A full list of description and related HS Codes is available authorities website.
It comprises about 5,000 commodity groups; each identified by a six digit code, arranged in a legal and logical structure and is supported by well-defined rules to achieve uniform classification.
The system is used by more than 200 countries and economies as a basis for their Customs tariffs and for the collection of international trade statistics. Over 98 % of the merchandise in international trade is classified in terms of the HS.
The HS contributes to the harmonization of Customs and trade procedures, and the non-documentary trade data interchange in connection with such procedures, thus reducing the costs related to international trade. A full list of description and related HS Codes is available on foreign-trade.com.
It is also extensively used by governments, international organizations and the private sector for many other purposes such as internal taxes, trade policies, monitoring of controlled goods, rules of origin, freight tariffs, transport statistics, price monitoring, quota controls, compilation of national accounts, and economic research and analysis.
Every product imported or exported should a require commodity code and will need to be shown on your invoice along with the description of the goods.
Export declarations use 8 digits whereas import declaration use 10 so whatever incoterms you will be using it is advised to be showing up to 10 digits on invoices of goods.