Cookies from Facebook

By: Richard Beaumont | Monday, July 11, 2011 | Tagged: Facebook | Leave Comment

We have started doing some analysis on some of the websites with the biggest collections of cookies in our database.

Whilst it is still early days, we think it is worth sharing what we have uncovered so far.

We recently decided to see how many unique cookies (by name) we had in our database from Facebook. The search came back with a staggering 155,000 cookies!

The vast majority of these are very similar, their names beginning with _e_ which is then followed by four characters which are a mixture of letters and numbers, then another underscore followed by a number which looks like it can be between 1 and 3 digits.

There are about 152,000 of these, and it looks like they are all session cookies - that are deleted after the browser is closed down.

Facebook's own privacy policy coverage of cookies is almost non-existent.  It simply states that they use cookies, but goes into no further details.

Which means of course that we cannot really know what these cookies are used for.  However it seems a safe bet that the shared nomenclature means they are intstances of a 'class' of cookies that almost certainly have a common purpose, but are generated dynamically in some way.

We have seen this kind of behaviour in many other large media sites - very large numbers of related but unique cookies.

Clearly getting consent for each of these cookies could pose quite a challenge, as you would have to explain what each of them does. 

Unless of course you are in Ireland.  As we pointed out in our blog last week, the Irish advice is that as session cookies, these would not need user consent, regardless of how intrusive they may be in privacy terms.

If anyone can throw some light on these cookies - we'd be very interested to hear from you.

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