Definition
NAICS Code
Also known as: North American Industry Classification System
A NAICS code is the six-digit numeric identifier used by federal agencies to classify business establishments by industry. The NAICS code assigned to a contract determines size standards for small-business set-asides, but does not by itself determine whether CMMC applies — that turns on the data type (FCI vs CUI), not the industry.
Primary source
U.S. Census — NAICS