Passport.js is a flexible authentication middleware for Node.js that can be added to any Express-based application. With Passport.js we can implement authentication using the concept of strategies.

Passport strategies are separate modules created to work with different means of authentication. Passport is a very extensible middleware, and it allows you to plug in over 300 different authentication providers like Facebook, Twitter, Google, and more.

In order to offer Passport-supported authentication, we’ll need to install and configure the strategies modules that we’d like to use. In this lesson, we’ll be focusing on a local Passport strategy, passport-local, and authenticating users using a username and password.

We can take a look at the diagram to get an understanding of the authentication flow through Passport.js, and we’ll go more in-depth as to how each step works in the following exercises.