A passwordless authentication system allows users to access an application without entering a password, instead using a secure token or biometric signature to verify their identity. The system created in this tutorial uses Twilio Verify and SendGrid to send a one-time password (OTP) to the user's registered email address after they attempt to log in. The OTP is then verified by the user, who enters it on the login page. If the OTP is correct, the user is authenticated and redirected to the home page. This system provides several benefits, including improved security against brute force attacks and credential stuffing.