> ## Documentation Index
> Fetch the complete documentation index at: https://auth0.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Identity-Provider-Initiated Single Sign-On

> Overview of Single Sign-on (SSO) initiated by Identity Providers (IdPs).

For Identity-Provider-Initiated <Tooltip tip="Single Sign-On (SSO): Service that, after a user logs into one applicaton, automatically logs that user in to other applications." cta="View Glossary" href="/docs/glossary?term=Single+Sign-On">Single Sign-On</Tooltip> (SSO), a third-party <Tooltip tip="Single Sign-On (SSO): Service that, after a user logs into one applicaton, automatically logs that user in to other applications." cta="View Glossary" href="/docs/glossary?term=Identity+Provider">Identity Provider</Tooltip> (IdP) is the SSO provider. When a user logs in to an application:

1. The application redirects the user to an identity provider.
2. The third-party identity provider performs authentication and authorization.
3. Upon successful authentication, the user is returned to the application.

Auth0 provides IdP-initiated [SSO Integrations](/docs/customize/integrations/sso-integrations) for various services, like [Dropbox](https://marketplace.auth0.com/integrations/dropbox-sso), [Slack](https://marketplace.auth0.com/integrations/slack-sso), or [Zoom](https://marketplace.auth0.com/integrations/zoom-sso). To see the full list, explore [Auth0 Marketplace: SSO Integrations](https://marketplace.auth0.com/features/sso-integrations).

You can also build your own implementation with SAML or OIDC:

* [SAML Identity Provider Configuration Settings](/docs/authenticate/protocols/saml/saml-identity-provider-configuration-settings)
* [Configure Applications with OIDC Discovery](/docs/get-started/applications/configure-applications-with-oidc-discovery)