QUOTE(Singh Deep @ Aug 20 2012, 01:08 PM)
How do you define CTR?
This is pretty straight forward and usually refers to one of the following:
If you have Adsense on your sites then it's the number of people who actually click on an ad divided by the number of people who saw an ad.
If you're running an Adwords campaign then it's the number of people who clicked on your ad divided by the number of people who saw your ad.
So lets say that your adverts was displayed 1,000 times and 45 people clicked in the ad, your click through rate is 4.5%