NAICS is the North American Industry Classification System. SIC is the older equivalent still carried on many records. Both attach a number to what a company does, which makes them handy for narrowing a search.
The catch is staleness. A company is coded once and rarely recoded, so a firm that changed what it does five years ago can still sit under the old number. Searching on codes alone quietly drops real prospects.
Buzzlist handles this by searching the plain-English descriptions behind the codes as well as the codes themselves, and by letting you pair an industry with the words a company would put in its own name.
