- From: Linss, Peter <peter.linss@hp.com>
- Date: Sun, 14 Aug 2011 06:47:22 +0100
- To: Jonathan Rees <jar@creativecommons.org>
- CC: "www-tag@w3.org" <www-tag@w3.org>
On Aug 12, 2011, at 8:11 AM, Jonathan Rees wrote: > Probably everyone knows this but me... > > I shop at expedia.com (or somewhere) for a London hotel room. Later I > visit guardian.co.uk and see an Expedia ad for London hotel rooms. > > I visit guardian.co.uk in a different browser (same computer & IP > address but Safari instead of Chrome) and instead get an ad for > magazine subscriptions. Apparently the Guardian can tell my two > browsers apart somehow - it's using more than just my IP address to > decide what ads to show me. > > How does this work? I.e. what are browser instances doing that leaks > their identity to servers? Is it just a lucky guess based on > User-agent or something? > > (a propos our privacy & tracking discussions) For the cross-browser tracking they're likely using Flash Local Shared Objects. The fact that the info is shared among browsers is most likely a happy accident, the intent is more to have a "cookie" that doesn't get cleared when browser cookies are cleared and also often bypasses regular browser cookie controls and privacy modes. Peter
Received on Sunday, 14 August 2011 05:49:13 UTC