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

> Learn about triggers, which are events that automatically invokes an Action when a specific operation, such as a user logging in, occurs at runtime.

# Explore Triggers

Triggers are points in the Auth0 process where Actions can be added for required customization. Multiple Actions can be placed in a Trigger, executing in sequence. Triggers can be synchronous (blocking) or asynchronous (non-blocking).
Each trigger has specific Objects and APIs. They may differ based on your connection (such as <Tooltip tip="Passwordless: Form of authentication that does not rely on a password as the first factor." cta="View Glossary" href="/docs/glossary?term=passwordless">passwordless</Tooltip> connection).

To explore reference Objects and APIs for specific Actions for a trigger, select the trigger below, noting Auth0's definition of a [passwordless connection](/docs/authenticate/passwordless).

#### Signup and Login

When a user is added to a database or passwordless connection (Signup), or as part of a user's authentication transaction (Login).

<table class="table">
  <thead>
    <tr>
      <th>Trigger</th>
      <th>Description</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td><code>pre-user-registration</code></td>
      <td>Triggers before a user is created.</td>
    </tr>

    <tr>
      <td><code>post-user-registration</code></td>
      <td>Triggers asynchronously after a user is created.</td>
    </tr>

    <tr>
      <td><code>post-login</code></td>
      <td>Triggers after a user is authenticated but before a token is issued.</td>
    </tr>
  </tbody>
</table>

#### MFA Notifications

When using SMS as a factor for <Tooltip tip="Multi-factor authentication (MFA): User authentication process that uses a factor in addition to username and password such as a code via SMS." cta="View Glossary" href="/docs/glossary?term=Multi-Factor+Authentication">Multi-Factor Authentication</Tooltip> (MFA) or to configure a custom provider.

<table class="table">
  <thead>
    <tr>
      <th>Trigger</th>
      <th>Description</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td><code>send-phone-message</code></td>
      <td>Triggers when using a custom provider to send the messages for the enrollment and the challenge process.</td>
    </tr>
  </tbody>
</table>

#### Password Reset

When a password reset request is initiated.

<table class="table">
  <thead>
    <tr>
      <th>Trigger</th>
      <th>Description</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td><code>post-change-password</code></td>
      <td>Triggers after a password is changed.</td>
    </tr>

    <tr>
      <td><code>password-reset-post-challenge</code></td>
      <td>Triggers after the first challenge is completed and before the password is reset.</td>
    </tr>
  </tbody>
</table>

#### Machine to Machine

When an application, instead of a user, is authenticated and authorized to use your APIs.

<table class="table">
  <thead>
    <tr>
      <th>Trigger</th>
      <th>Description</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td><code>credentials-exchange</code></td>
      <td>Triggers before an access token is returned.</td>
    </tr>
  </tbody>
</table>