OpenID Connect allows a user to authenticate to an App, a service or a site (generically termed a Relying Party, or RP) using an identity establish with another system, called the Identity Provider (IdP). Well known IdP’s include Google and Facebook.

1. OpenID Connect sso authentication a simple JSON/REST-based interoperable identity
protocol built on top of the OAuth 2.0 family of specifications. Its design philosophy is
‘make simple things simple and make complicated things possible’.
While OAuth 2.0 is a generic access authorization delegation protocol, thus enabling
the transfer of arbitrary data, it does not define ways to authenticate users or
communicate information about them. OpenID Connect provides a secure, flexible, and
interoperable identity layer on top of OAuth 2.0 so that digital identities can be easily
used across sites and applications.
OpenID Connect allows a user to authenticate to an App, a service or a site (generically
termed a Relying Party or RP) using an identity establish with another system, called
the Identity Provider (IDP). Well known IDP’s include Google and Face book.
The simplest deployment of OpenID Connect allows for clients of all types including
browser-based, mobile, and javascript clients, to request and receive information about
identities and currently authenticated sessions. The specification suite is extensible,
allowing participants to optionally also support encryption of identity data, discovery of
the OpenID Provider, and advanced session management, including logout.

2. How is OpenID Connect different than OpenID 2.0, SAML & OAuth?
OpenID Connect performs many of the same tasks as OpenID 2.0, OAuth and web
access management system, but does so in a way that is standardized and API-friendly.
OpenID Connect can also be extended to include more robust mechanisms for signing
and encryption. Integration of OAuth 1.0a and OpenID 2.0 required an extension
(called the OpenID/OAuth hybrid); in OpenID Connect, OAuth 2.0 capability is built
into the protocol itself. The following graphic presents a concise summary as to why
OpenID Connect is positioned for mass enterprise and customer adoption.
In OpenID Connect, the jargon has been altered (surprise!) and here are a few terms
you should be familiar with:
OpenID Connect Provider (OP): This is the equivalent of an IdP in SAML.
Relying Party (RP): What used to be SP’s, are now RP’s in OpenID Connect.
Clients: Clients are websites, apps, and devices.
Claims: Claims are groups of attributes that are released to Clients.
Article resource:-https://sites.google.com/site/thegluuserver/openid-connect-turns-sso-
into-a-standard-oauth--protected-identity-api