Any webmaster trying to achieve top search engine placement needs to be familiar with DirectHit and other click-tracking technologies. With click popularity and stickiness DirectHit claims to allow users, rather than search engines or directory editors, to organize search results. Click popularity is a measure of the number of clicks received by each site in a search engine's results page. If, after scanning the first 10 results, all the users click on the Smith Brothers Dog Food site, a click-tracking technology assumes Smith Brothers' site is more relevant to users than the other sites in the top 10. Next time someone searches for puppy food, Smith Brothers' site will have a higher ranking in the results.
Stickiness is a measure of the amount of time a user spends at a site.
It's calculated according to the time that elapses between each of the user's clicks on the search engine's results page. You get a page with 10 sites to visit. You click on the first one and wander off for 20 minutes. Then you come back to the results page and click on the next site. It turns out to be irrelevant, so you go on to the third in about 20 seconds.