Translations:Manual:$wgAllowExternalImages/23/en

Now with external images enabled, a user can be fetching images from other webservers. A malicious (or devious) person could make wiki edits to set up an external image URL on your wiki, purely for the purpose of gathering this data about your visitors. No need to panic! They wouldn't get credit card numbers or anything, just the kind of data that is sent every time you visit a website. But this might allow them to build up a (rather fuzzy) picture about visitors to your site, which might be correlated with similar data from other sites, and could potentially give rise to privacy concerns. It's the kind of data that has a value to marketing companies, a list saying "The person on this IP address is interested in this kind of website"