Third-party authentication services provide an alternative way how users can log in and register to your site. This way, they do not need to go through the registration process and create a new username and password for your site. Instead, they can use some username and password that they already use on some popular site (like Windows Live, Facebook, Google, Yahoo!, etc.). Even new users can log on to your site like this, in which case a new user account is created.
Kentico CMS supports the following three authentication providers:
Click the links above to learn more about how to set up authentication using the particular provider.
Page url: http://devnet.kentico.com/docs/5_5r2/devguide/index.html?3rd_party_auth_overview.htm