Authentication Simplified: The Four Core Concepts Behind Every System

Developers often face a bewildering array of authentication terms—OAuth, JWT, sessions, and API keys—that seem like entirely separate systems. This breakdown reveals they're all variations of just four core concepts: identity (your claim of who you are), credential (proof of that claim), session (a reusable permit), and token (a signed credential). Grasping these fundamentals enables architects to design more secure systems and developers to implement auth correctly across different platforms and protocols.