Overview
Authentication is the process of verifying the identity of a user, device, or system before granting access to resources. It is a fundamental part of Web Development and security practices.
Common Methods
- Password-based: Users log in with a username and password.
- Token-based (JWT, OAuth2): Issues tokens for session management and API access.
- Session-based: Uses cookies and server-side sessions to track authentication.
- Multi-Factor Authentication (MFA): Adds additional layers like OTP, biometrics, or hardware keys.
- Social Login: Uses third-party identity providers like Google, GitHub, or Microsoft.
Key Concepts
- Authorization vs Authentication: Authentication verifies who you are, while authorization determines what you can access.
- Identity Providers (IdP): Services that manage user credentials and identities.
- Access Tokens & Refresh Tokens: Short-lived tokens for requests, with refresh tokens to extend sessions.
Use Cases
- Protecting restricted pages and resources.
- Enabling user accounts and personalized experiences.
- Securing APIs and backend services.
- Implementing single sign-on (SSO) across apps.
Tools & Libraries
- Frontend: MSAL.js, Firebase Auth, NextAuth.js
- Backend: Passport.js, Auth0, Keycloak
- Standards: OAuth2, OpenID Connect, SAML
Purpose
Authentication helps in establishing a trusted identity layer so apps can safely decide what a user or service can do. It protects sensitive resources, enables personalization, and underpins authorization, auditing, and compliance.