an advertisement on the Internet that you can click on for more information, and which allows the advertiser to know how many people are interested enough in their advertisement to do this:
Click-throughs are one of the standard ways to measure the effectiveness of online ads.
click-through rates
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.
Dictionary pictures of the day
Do you know what each of these is called?
Click on any of the pictures above to find out what it is called.