En este caso parece ser terminología específica de marketing por internet. No sólo es hacer clic sobre algo, sino que ese algo es un banner que deriva al sitio en cuestion (el sitio del anunciante). Dependiendo del contexto tendrás que adaptarlo. Ayudaría la frase completa.
Saludos =:)

Click Troughs, Raw Hits and CPM

To understand web advertising you first need to understand some terminology. A "banner ad" is a graphic image (or gif file) that measures approximately 468 pixels wide by 60 pixels high, and weighs in at around 7.5 kilobytes. The term "hits" means the number of files (downloaded by a visitor's browser) from your site. This includes all graphic image files and HTML page files. The number of visitors who view a page (or a banner ad) is known as "page impressions" or "views". The cost per thousand impressions or page views is referred to as "CPM" (that was obvious). When a visitor clicks on your banner ad (and they are transported to your web page), this is referred to as a "click through". The "click rate" represents the percentage of visitors who "click through".
http://www.adspeak.com/toolbox_4.html