> For the complete documentation index, see [llms.txt](https://kdongs.gitbook.io/kdocs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kdongs.gitbook.io/kdocs/openid-connect-protocol/openid-connect.md). # OpenId Connect ## About {% hint style="warning" %} `OpenID` = `OAuth 2.0` + Authentication. {% endhint %} {% hint style="info" %} OpenID 1.0 allows user to authenticate in different sites using a single identity, but this version has several limitations and security vulnerabilities. In 2007 it was replaces by OpenID 2.0 which incresed security, added multi-factor authentication resources and added support for several identity providers. {% endhint %} OpendID is a token based authentication layer over [OAuth 2.0](/kdocs/openid-connect-protocol/oauth-2.0.md) protocol. It was created to provide federated authentication in Web and Mobile apps, allowing users to login in different apps using the credentials of a single identity. It is based in concepts like: * Authentication flows; * Access Tokens; * Tokens updates; * Checkable Identities.