The document discusses using OpenID Connect to enable social single sign-on for Salesforce users. OpenID Connect is an identity layer built on top of OAuth 2.0 that allows users to authenticate using their existing credentials from identity providers like Google, Microsoft, and PayPal. It describes how to set up OpenID Connect with Salesforce as the relying party by registering as an OAuth client, configuring an auth provider in Salesforce, and defining user management logic using a registration handler.