Simplifying Global E-commerce
The Harmonized Tariff Schedule is descriptive nomenclature maintained by the World Customs Organization. The HTS can be access at the WCO's World Trade Tools.
Each country maintains its version of the HTS for the customs duty rates assessed on imports into the country.
For the USA, the Harmonized Tariff Schedule of the United States (HTSUS) is maintained by the U.S. International Trade Commission at https://usitc.gov under HTS or at Harmonized Tariff Schedule PDFs (usitc.gov). Additionally, U.S. Customs and Border Protection (CBP) has the Customs Rulings Online Search System (CROSS) to research how CBP has classified goods under the HTSUS.
Note that the HTS will be updated in 2022.