There are three standard classification systems for merchandise trade globally:
Many countries build on the HS by adding additional digits to tailor it to their needs. All imported and exported goods must be classified for Customs purposes. Each product is assigned a particular classification code.
In the United States, we have Schedule B for exports and the Harmonized Tariff Schedule (HTS) for imports. The next section contains additional information on these classification systems.
The NAICS is the North American Industry Classification System. It is the standard used by Federal statistical agencies in classifying business establishments for the purpose of collecting, analyzing, and publishing statistical data related to the U.S. business economy. It was developed jointly by the US, Canada, and Mexico in 1997 to replace the SIC. The U.S. Census Bureau hosts the search, documentation, and history of the system. It is a 2-6 digit industry (not product) code. The first two digits designate the sector, the third designates the sub-sector, the fourth designates the industry group, the fifth designates the NAICS industry, and the sixth designates the national industry.
SIC is the Standard Industrial Classification System, a 4-digit code for classifying industries. It was created by the United States in 1937. It has been superseded by the NAICS system, but it is still in use academically and by some other countries. The first 2 digits represent major industry sectors, the 3rd digit describes a sub-classification of a sector, and the 4th digit identifies a specific industry sector.
The United States has its own classification system - Schedule B. It is managed by the Foreign Trade Division in the U.S. Census Bureau. Schedule B codes are 10-digit identifiers assigned to products exported from the US. The first six digits are the same as the HS code. The last four digits are an extension used only by the US for statistical purposes.
The United States has its own import classification system, called the Harmonized Tariff Schedule (HTS) which is managed by the International Trade Commission. The first six digits are the same as the HS code. The last four digits are an extension used only by the US to track imports. New schedules are published at the beginning of the year.
The Harmonized System (HS) is the global system developed and maintained by the World Customs Organization that is used by most countries to harmonize commodity description and coding. These are 6-digit codes that are 'globally harmonized' - every country using the codes will use the same code for their products. HS is governed by "The International Convention on Harmonized Commodity Description and Coding System".
The ISIC is the International Standard Industrial Classification of All Economic Activities system. It was developed in 1948 by the United Nations Statistical Commission. It is a 4-level structure. A letter designates the section, a two digit code designates the division, the third digit designates the group, and the fourth digit designates the class. The current version is revision 4, 2008. It is available online, in print, and downloadable from the UN. The NACE and ISIC have exactly the same items at the highest levels, but NACE is more granular at lower levels.
NACE is the Nomenclature of Economic Activities. The European Community Statistical classification of economic activities for the European Union. It is a four level hierarchical system that uses a 4-digit classification system. Level 1 uses letters A-U for Sections (Countries). Level 2 uses 2-digit numerical codes for divisions, level 3 uses one digit for groups, and level 4 uses one digit for classes. The current version is Rev. 2 (2008). Code list. The NACE and ISIC have exactly the same items at the highest levels, but NACE is more granular at lower levels. Additional documentation is available from the EC.
The Standard International Trade Classification (SITC) is a statistical classification system developed by the UN to facilitate the comparison of import and export trade internationally. It is based on the Harmonized System (HS) and covers all classifiable goods except bullion. It uses 1-5 digit codes.
Historical SITC data is available from the US Census Bureau.
The UN maintains several other Statistical Classifications:
Resources for Classifications on economic statistics: CPC, HS, ISIC, COICOP, SITC, BEC, ICATUS, EBOPS, COFOG, COPNI, COPP.
They also maintain information on National Classifications which currently include 909 classifications from 159 countries.