Introduction to Authentication and Authorization

🌍 Introduction

In modern applications, security is critical. APIs need a way to verify users (authentication) and control what they can access (authorization).

In this lesson, you'll learn:

• What authentication and authorization are.
• The key differences between them.
• Common authentication methods used in APIs.
• Why secure authentication is important.

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📌 1. What is Authentication?

Authentication is the process of verifying who a user is.

Example:

• When you log into a website with a username and password, the system authenticates you.
• If your credentials are correct, you’re granted access.

🔹 Common Authentication Methods:

Method	Description
Username & Password	The most basic form of authentication.
Session-based Authentication	Stores login sessions on the server.
Token-based Authentication (JWT, OAuth)	Uses tokens instead of sessions.
OAuth (Google, GitHub login, etc.)	Allows third-party authentication.
API Keys	A secret key used for authenticating API clients.

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📌 2. What is Authorization?

Authorization determines what a user can do after being authenticated.

Example:

• A regular user can only access their own profile.
• An admin can manage all users.

🔹 Common Authorization Methods:

Method	Description
Role-Based Access Control (RBAC)	Users are assigned roles (Admin, User, Moderator, etc.).
Attribute-Based Access Control (ABAC)	Access is based on attributes (e.g., location, department).
Permission-based Authorization	Users are granted specific permissions (e.g., "Can Edit Posts").

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📌 3. Authentication vs. Authorization

🔹 Authentication → "Who are you?"
🔹 Authorization → "What are you allowed to do?"

Feature	Authentication	Authorization
Purpose	Identifies a user	Grants user permissions
Happens When?	Before authorization	After authentication
Example	Logging in with a password	Checking if a user can access an admin page
Technologies	Passwords, JWT, OAuth	RBAC, permissions

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📌 4. Why Authentication & Authorization Matter

🔹 Security: Prevents unauthorized access to sensitive data.
🔹 User Control: Ensures users only access what they should.
🔹 Compliance: Many industries require strict access control (GDPR, HIPAA).

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📌 5. Real-World Example

Imagine a Todo List API:

User Type	Can Access
Guest (Unauthenticated)	❌ Cannot create tasks
Authenticated User	✅ Can create, edit, and delete their own tasks
Admin	✅ Can manage all tasks

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🎯 Summary

• Authentication verifies who you are.
• Authorization controls what you can do.
• Both are essential for API security.
• APIs commonly use JWT, OAuth, and RBAC to manage access.

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✅ Next Lesson: Understanding How Authentication Works in APIs

In the next lesson, we’ll explore how authentication works behind the scenes and introduce JWT (JSON Web Tokens). 🚀