Understanding Passport & OAuth Authentication

Authentication verifies user identity, often with username/password logins. Passport is a Node.js middleware simplifying authentication via flexible strategies. Passport supports numerous strategies like username/password, Google, and Facebook, integrating well with Node.js frameworks. A Passport strategy is a plugin defining the authentication method, such as `passport-local` or `passport-google-oauth20`. OAuth is an authorization protocol allowing users to share data access without revealing passwords. OAuth2 involves redirecting users to a provider for login, obtaining authorization, and exchanging a code for an access token. Passport integrates with OAuth and frameworks like NestJS through strategy setup and route configuration. A practical NestJS example involves installing Passport, setting up a Google strategy with client credentials, and creating controller routes for login and callback. After successful login, the user's information is available for saving to a database or creating a session. Securing client secrets and using environment variables is essential, and strategies can be extended for various platforms.