Software → Security
Authentication
The process of verifying who a user, service, or system claims to be.
Where it fits
Authentication establishes who a user, service, or device is. It appears in product features, API security, web applications, and operations tooling.
Mental model
Authentication answers: “Who are you?” Authorization answers: “What are you allowed to do?”
Example
A user signs in with a password and multi-factor code. The system creates a session or token that represents the authenticated identity.
Common mistakes
- Confusing authentication with authorization.
- Storing passwords directly instead of password hashes.
- Treating JWTs as automatically secure.
Related concepts
Authorization, session, cookie, JWT, OAuth, password hashing.