OAuth
An open standard for secure authorization allowing third-party access without sharing passwords.
Definition
OAuth is an open authorization standard that enables users to grant third-party applications limited access to their accounts without sharing passwords. OAuth 2.0, the current version, uses access tokens to authorize specific actions.
The protocol defines flows for different application types (web, mobile, server-to-server) and scopes that limit what authorized applications can access.
Why It Matters
OAuth enables the "Sign in with Google/Facebook/etc." buttons that streamline user registration while maintaining security. It's also how APIs authorize access to user data without exposing credentials.
Understanding OAuth flows is essential for developers building applications that integrate with third-party services.
Examples in Practice
"Sign in with Google" using OAuth to authenticate users without your app seeing their Google password.
A marketing tool requesting OAuth access to post on users' LinkedIn accounts.
Scope limitations allowing an app to read emails but not delete them.