The North American Industry Classification System (NAICS) are a set of codes. Each code is unique to a specific industry. These codes can be used in many databases and websites for researching that industry. They were developed in the late 1990s by the U.S. Office of Management and Budget (in collaboration with agencies from Mexico and Canada), and largely (though not completely!) replaced the Standard Industrial Codes (SICs). You may still find the need to use SICs in addition to the NAICS codes when researching an industry. Keep in mind that some companies may create products or services that fall into multiple industries.