# Authentication

This chapter describes various ways to authenticate to Continuwuity.

## Authentication flows

Continuwuity implements the following authentication flows:

- **OAuth login** (also known as **next-gen auth**): clients redirect the user to Continuwuity's login/signup page.
- **Legacy login** (also known as the **UIAA** framework): clients logs in/signs up directly to the server via its own UI.

Different sets of clients support different flows, but most clients are moving towards next-gen auth. One can set which login mode(s) are allowed via the `compatibility_mode` variable of the `[global.oauth]` config file section.

## Authentication sources

Continuwuity can read user authentication data from the following sources:

- **Internal database** - this is the default setup, which allows for self-service registration and email configuration.
- **Delegated authentication** - the server connects to an OpenID Connect identity provider for user authentication. This is useful for Single-Sign On against a central identity directory.

:::important Delegated authentication and legacy logins
When configuring Delegated authentication, **legacy login will be implicitly disabled** and local passwords made redundant.
:::

## Further reading

See the following pages for further details:

- [**Registration and email configuration**](./authentication/registration)
- [**Delegated authentication**](./authentication/oidc)