The following is an excerpt from an article by Michael Keating for GovPro Magazine:
No question about it: The NIGP Commodity/Services Code (NIGP Code) has become THE national standard for product/service codes used in public purchasing in the United States. It is used at some level by 33 states and thousands of local jurisdictions and political subdivisions.
The NIGP Code features an extensive library of descriptive terms, assembled, indexed and organized into a comprehensive classification structure to identify and describe a wide variety of products and services. All in all, the NIGP Code offers an effective coding structure for standardizing purchasing.