Many government and business publications use Codes to index companies and economic data. You may need some of these codes to do your research in a variety of resources.
For European industries, use: NACE codes.
If you need to convert NAICS to NACE (or vice versa), see: Eurostats Index to Corresponding Tables
For Australia and New Zealand, use: ANZSIC.
For Japan, use: JSIC.
For the United Nations, use: ISIC or ISCO.