The invention enables and/or facilitates the display of personalized content to content observers by content providers (e.g., advertisers) who disseminate content over a network. The invention enables identification of particular content observers at a content display site using analysis of content observation behavior at a content display site, data regarding one or more physical characteristics of content observers in the vicinity of the content display device during display of particular content, and/or analysis of demographic characteristics of possible content observers at the content display site. The invention prevents unauthorized access to data produced as part of identification of the content observer.