Today in my site statistics it shows the average number of visitors but twice as many page hits. Of course, this could be a simple, random inconsistancy. However, if this continues I may begin to attribute it to hotlinking/stolen bandwidth. I haven't made any significant bandwidth-raising change to the site in the last day.
Is there a way to check if another site is calling in my files?
A hit is any file requested by the user from server, images/javascript/css included. It's fully normal to have less pageviews or unique visitors than hits (in fact I'd be surprised if it was the other way around).
As far as checking if someone is hotlinking, viewing your raw access logs for HTTP_REFERER would be a good idea. Finally, you should protect your image folders from hotlinking with mod_rewrite anyways.
All servers contain a log of all acivities. Are you using CPanel? Just go to statistics if you are and the logs usually display the information needed.
If you have AWStats, then look at entry page. If lots of them are an image or a download, then people are hotlinking to your files. If it is an actual page, well, that is all gravy. You do want visitors after all.
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