What is ClickBank tracking ID?
Tracking ID is an alphanumeric identifier which helps you track your traffic. For example, ClickBank Tracking ID can help you determine which affiliate campaign works better. When you use the same ClickBank feed on two different websites and want to know which one brings more conversions, you can use different tracking IDs for these websites. So you use "website1" and "website2" as tracking IDs in your affiliate feed.
Then in your ClickBank account, you will see which tracking ID brings more results.