SSO with OpenID
OpenID is a Single Sign On (SSO) system, allowing you to use same account name for logging into different websites. In simple words, the user does not have to register in your website to access the website, he or she can just use his or her OpenID credentials to log in to your website. There are many OpenID providers, the popular ones being Yahoo! and Gmail. So, you can use your Yahoo! or Gmail credentials to get into the Liferay website.