Put simply a call to action is a message and a button on a zubbit link which is displayed on a page you share.
So the Call-To-Action is made up of two elements, the first being the message and the next being a button and some action text on it. They can be used on one zubbit link or more likely re-used on lots of zubbit links so they all do the same thing when displayed.
Call-to-Actions contain groups of zubbit links sharing common characteristics. Call-to-Actions contain your message and action link along with your customisation settings. Every zubbit link belonging to a single Call-to-Action will share those settings.
For example, Call-to-Action A can contain a blue button linking to mashable.com. If there are 30 ZUBB’s assigned to Call-to-action A, then all 30 zubnit links will contain the blue button linking to mashable.com.
Any changes I make to Call-to-Action A will apply to all 30 zubbit links. Any new zubbit links I create under Call-to-Action A will also reflect these settings. Call-to-Actions are great for organising groups of zubbit links and segmenting the analytics for different marketing initiatives.
You can use your call-to-actions on any brands you want so are completely flexible and re-usable.