While it is well worth FB users reading and understanding the extent and consequences of (and defence against) the FB widget web I thought it worth mentioning that tracking by widget or app is not restricted to FB. Or even to sites requiring registration. Nor is the idea or it's practice new.
Let us take that most open innocuous type of site, the information site, that wants to better (more accurately) segment it's audience, better target conversion offerings, etc. No registration required, come one come all.
Create one or more widgets/apps that complimentary sites (even competitor sites
) will be willing to insert on their pages. Include a cookie or other identifier. As the person browses about the web each time they visit a page with the widget/app it collects, stores, and should they finally show up on the widget providers site drops data. Depending on the reach and saturation of the widgets/apps the additional information could be marginal to definitive.Should the site be (or be affiliated with) an ecommerce site real personally identifiable information can be combined with previous browsing history enabling highly targeted followup and up-sell opportunities. As with FB one could, at a minimum, better target one's direct sale ads for improved performance and so justify higher rates.
Remember several years back when javascript was being used to read CSS visited link colour of a preset list of URLs? Well the methods have become far more complex and pervasive since then. The above is but the tip of the current visitor data tracking/mining, the naive olden days.
And it is only going to become deeper and darker.
