Plone is a very robust content management system right out of the box. Check to see if the feature you want is already supported in Plone. Sometimes you may want to add additional functionality to meet your own unique needs. You can research and download add-on products for Plone here: http://plone.org/products . Plone add-on products give you the ability to choose functionality for your site that meets a specific use case. All you have to do is download and install! Be careful that the product you are installing is up to date for your version of Plone. Also, look at the release dates. You want to chose a product that is supported and people are still using. If the product hasn't been updated in a year, it may be using it at your own risk. Add-on products give you more options than basic Plone.