WSO2’s Identity and Access Management Solution, Identity Server, allows you to introduce Federated Authentication in your IT landscape.
With Federated Authentication we mean that we use a third party (a so called Identity Provider) to authenticate a user.
Rather than keeping a separate and own user registration, authentication is done by a third party for instance Facebook, Google or another service.
We should clarify, btw, that is is not a question of either / or but rather question of choice. You can have a local authenticator and / or federated authenticator(s).