> ## Documentation Index
> Fetch the complete documentation index at: https://docs-staging-docs-event-stream-action-templates.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Add user authentication to your application with Auth0, including login flows and connections to external identity providers.

# Authenticate

In authentication, a user or application proves they are who they say they are by providing valid credentials. The most common verification is password, often combined with other methods, such as a fingerprint.

Auth0 simplifies the use of open industry standards like OAuth 2.0, OIDC, and SAML to authenticate. Users can log into your applications with social media credentials, corporate accounts, and a broad range of other credentials.

***

## Add Login

##### Implement Auth0 Universal Login (or an alternative) to control access to your applications.

<Card title="Login" href="/docs/authenticate/login">
  Choose from a variety of user login options.
</Card>

<Card title="Single Sign-On" href="/docs/authenticate/single-sign-on">
  Enable users to log in to one application and automatically authenticate in other applications.
</Card>

<Card title="Passwordless" href="/docs/authenticate/passwordless">
  Let users enter mobile phone numbers or email addresses and receive a one-time code or link to log in without a password.
</Card>

<Card title="Custom Token Exchange" href="/docs/authenticate/custom-token-exchange">
  Learn about Custom Token Exchange Early Access features.
</Card>

***

## Provision Users

##### Source users from social identity providers (such as Facebook or SalesForce), enterprise user stores (such as Active Directory or Google Workspace), a custom database, and more.

<Card title="Identity Providers" href="/docs/authenticate/identity-providers">
  Set up sources of user accounts to authenticate your applications and APIs.
</Card>

<Card title="Database Connections" href="/docs/authenticate/database-connections">
  Authenticate users with an email/username and password and save their credentials in an Auth0-provided user store or in your own database.
</Card>

<Card title="Enterprise Connections" href="/docs/authenticate/enterprise-connections">
  Authenticate users with external, federated identity providers such as Azure AD, Google Workspace, and PingFederate.
</Card>

<Card title="Protocols" href="/docs/authenticate/protocols">
  Easily implement open industry-standard protocols like OAuth 2.0, SAML, and LDAP for authentication and authorization.
</Card>

<Card title="Connection Settings Best Practices" href="/docs/authenticate/connection-settings-best-practices">
  Review best practices when configuring social and database connections.
</Card>