When you create your website on NationBuilder, as supporters sign up the system automatically generates a public personal profile page for that user. This page shows all of the actions the user has taken on the site, as well as their Facebook and Twitter profiles (as long as they have linked them to their account).
This public profile allows users to interact with each other in a number of ways. When users promote your site to their Facebook and Twitter feeds or in an email, NationBuilder gives them credit in the form of Political Capital when their friends visit the site. Political Capital allows you, as well as other users, to see which followers are most influential and best at recruiting followers to your site. Users can also find other friends who have linked their social networking sites to their accounts. Public profiles function as a means of finding other posts by a particular user, see whether they've pledged their support, made suggestions, etc.
NationBuilder feels confident that their privacy settings are appropriate and well thought out. However, if you would like to turn off public profiles on your site here's how:
From the NationBuilder Control Panel click on Pages ---> Settings ---> Basic ---> then unclick the "Show public profile" box.