| Term | Definition |
| 2FA | Two-factor authentication |
| FRR | False rejection rate |
| FAR | False acceptance rate |
| CER/EER | Crossover error rate/equal error rate |
| IDaas | Identity as a Service |
| Kerberos | Ticketing-based authentication protocol |
| SESAME | Secure European System for Applications in a Multi-vendor Environment |
| RADIUS | Remote Authentication Dial-In User Service |
| TACACS | Terminal Access Controller Access Control System |
| XTACACS | TACACS with separate authentication, authorization, and auditing processes |
| Diameter | Similar to RADIUS and TACACS+ with increased flexibility |
| PAP | Password Authentication Protocol |
| CHAP | Challenge-Handshake Authentication Protocol |
