Quote:
An Impression (view) is, depending on what's meant, either an Ad Impression (Ad view) or a Page Impression (page view). Usually an Ad impression is what is meant. There can be multiple Ad impressions per page impression. Impression counting should consider that a small percentage of users choose to turn the graphics off (not display the images) in their browser.
Quote:
This form of site leeching can be prevented through the use of an .htaccess file with the various names of known Whacker program's 'User Agents' defined in the file code. By placing the full re-write syntax structure into the .htaccess file and referring the User Agent to some place else to ‘whack,’ anytime a Whacker program (as defined in the list) is detected, it will be halted from whacking your site and redirected elsewhere instead.