Each group has some letter (codes) after their brief description.
Each member group has up to three letters at the end of its description. These National Taxomony of Exempt Entities (NTEE) letter codes were developed by the National Center for Charitable Statistics to help a donor find organizations by a category listing that best defines their work missions, particularly useful when using an on-line search engine.
The 26 major groups are:
| A~Arts, Culture, and Humanities | N~ Recreation, Sports, Leisure, Athletics |
| B~ Educational Institutions & Related Activities | O~Youth Development |
| C~Envir. Quality, Protection & Beautification | P~Human Services – Multipurpose and Other |
| D~Animal Related | Q~International, Foreign Affairs, National Security |
| E~Health – General and Rehabilitative | R~Civil Rights, Social Action, Advocacy |
| F~Mental Health, Crisis Intervention | S~Community Improvement, Capacity Building |
| G~Disease, Disorders, Medicinal Disciplines | T~Philanthropy, Voluntarism, and Foundations |
| H~Medical Research | U~Science & Tech Research Institutes Services |
| I~Crime, Legal Related | V~Social Science Research Institutes, Services |
| J~Employment, Job Related | W~Public, Social Benefit: Multipurpose, Other |
| K~Food, Agriculture, and Nutrition | X~Religion Related, Spiritual Development |
| L~Housing and Shelter | Y~Mutual/Membership Benefit Orgs., Other |
| M~Public Safety, Disaster Preparedness & Relief | Z~Other |