To give customers the ability to login with their Facebook and Twitter credentials, the identity architect should configure a predefined authentication provider for Facebook and a predefined authentication provider for Twitter. Authentication providers are configurations that enable users to authenticate with an external identity provider and access Salesforce resources. Salesforce provides predefined authentication providers for somecommon identity providers, such as Facebook and Twitter, which can be easily configured with minimal customization. Creating a custom external authentication provider is not necessary for this scenario. References: Authentication Providers, Social Sign-Onwith Authentication Providers