The number of trackable URLs that have been clicked. This number may be greater than the number of opens or recipients if recipients click on a trackable URL multiple times, or if there are multiple trackable URLs in your message that recipients are clicking on.
The number of visitors who click on a specific advertising banner on a specific Web site or page.
The number of surfers who click on an ad and are sent to the sponsor's site. Legitimate click-throughs are often measured as Unique Hits. Some advertising programs pay a small amount ($0.01 - $0.20) per click-through, although the number of these programs is being reduced by widespread cheating. This may also be expressed as a ratio of Click-Throughs to total Impressions.