| Expertise | The actual knowledge, skill, and insight acquired through rigorous, domain-specific study and practice. Real and enduring. |
| Expert | A person who possesses expertise. (They may or may not be part of an institutional class). |
| Expert Class | The socially and institutionally recognized stratum of people who are labeled, credentialed, and given authority as "experts" in public discourse. This is a socio-political role, not just (or even necessarily) a function of real expertise. |