Ok cookies could be problematic enough so that some persons block them. Now, what about web beacons?...
Quoting a MS term of use:
"(...) [We use] web beacons or similar technologies from third-party analytics providers, which help us compile aggregated statistics about the effectiveness of our promotional campaigns or other operations. These technologies enable the analytics providers to set or read their own cookies or other identifiers on your device, through which they can collect information about your online activities across applications, websites or other products. However, we prohibit these analytics providers from using web beacons on our sites to collect or access information that directly identifies you (such as your name or email address). You can opt out of data collection or use by some of these analytics providers by clicking the following links:
"(...) [We use] web beacons or similar technologies from third-party analytics providers, which help us compile aggregated statistics about the effectiveness of our promotional campaigns or other operations. These technologies enable the analytics providers to set or read their own cookies or other identifiers on your device, through which they can collect information about your online activities across applications, websites or other products. However, we prohibit these analytics providers from using web beacons on our sites to collect or access information that directly identifies you (such as your name or email address). You can opt out of data collection or use by some of these analytics providers by clicking the following links:
• AppsFlyer: www.appsflyer.com/optout (https://www.appsflyer.com/optout)
• Flurry Analytics: https://aim.yahoo.com/aim/us/en/optout/ (https://aim.yahoo.com/aim/us/en/optout/)
• Google Analytics: tools.google.com/dlpage/gaoptout (http://tools.google.com/dlpage/gaoptout) (requires you to install a browser add-on)
• Kissmetrics: kissmetrics.com/user-privacy (https://kissmetrics.com/user-privacy)
• Mixpanel: mixpanel.com/optout (https://mixpanel.com/optout)
• Nielsen: www.nielsen-online.com/corp.jsp?section=leg_prs&nav=1#Optoutchoices (http://www.nielsen-online.com/corp.jsp?section=leg_prs&nav=1#Optoutchoices)
• Omniture (Adobe): www.d1.sc.omtrdc.net/optout.html (http://www.d1.sc.omtrdc.net/optout.html)
• Visible Measures: www.visiblemeasures.com/viewer-settings-opt-out (http://www.visiblemeasures.com/viewer-settings-opt-out)
• WebTrends: ondemand.webtrends.com/support/optout.asp (https://ondemand.webtrends.com/support/optout.asp) "
Quoting wikpedia (link above):
"A web beacon or web bug is one of the various techniques used on web pages or email, to unobtrusively (usually invisibly) allow checking that a user has accessed some content. Common uses are email tracking and page tagging for web analytics. Alternative names are tracking bug, tag, or page tag, tracking pixel, pixel tag, 1×1 gif, and clear gif. When implemented using JavaScript, they may be called JavaScript tags."
