Social plugins help developers and publishers drive growth and engagement for their websites with a single line of code. For example, social plugins allow people to easily share interesting content with their Facebook friends through News Feed. Examples include:
Like Button - people can share a web page or a piece of content with their friends in one click.
Subscribe Button - people can follow their favorite public figures in one click.
Comments Plugin - people can easily comment on articles, see the most relevant comments and share their comments with friends on Facebook.
Single Sign On Registration Plugin - enables people to login without having to fill in registration forms or remember another user name and password.