I a using statcounter.com for individual tracking. the visitros that have visited from PPC or adsense have a gclid with the page url.
Example:

http://www.iexpertsforum.com/top-seo-tools.html?gclid=CJiaoqyBk5cCFRTkbgod0mQV9w

How can I find which adin my campaign , the user clicked??
How can I track ads performance with Google analytics

can I decode this gclid??