What's the difference between "Primary" and "Secondary" terms?
"Primary Terms" are those terms that most simply describe your industry or offering, whereas Secondary Terms" have some additional term or word attached to it that makes it longer - and therefore less competitive. Generally, the longer the phrase the less they cost per click because there is less of a chance that someone will click that exact phrase. The upside though, is that less clicks per phrase on a less competitive term usually means a lower cost per click overall.
These tools are very new and we are still learning how to use them effectively.