The Harmonized System (HS) is an international classification system administered by the World Customs Organization. The 2-, 4-, and 6-digit HS headings and subheadings are the basis for the 10-digit statistical classification systems used in the United States. The HS is revised approximately every five years. For more information, see The World Customs Organization.
In the United States, the import classification system is called the "Harmonized Tariff Schedule of the United States Annotated (HTSA)" while the export system is called the "Schedule B".