When you did an request for a web page on their network, Verizon would silently add an header to your request with an ID tied to your data plan contract. The point was to enable them to sell analytics services that tracked users from their network across the sites of their clients.
If they can sell you and get paid by you for the privilege, why wouldn't they? Capitalism, as a good and effective market philosophy, is built on all parties being aware of all aspects of the transaction and ideally of all transactions... a perfect market. If such a thing doesn't exist, which it does not, then it's selective fuckery. However, it tends to exhibit less fuckery than most other systems... except when it doesn't.
well, it's more like, "You may be the product even if you're paying. Who knows because nobody will tell you because they're not required to tell you." But yeah, 'you are the product' is probably the most accurate.
It's a cookie that applies across all browsers and devices, and you cannot remove it. There is no way to opt-out of this tracking.
Analytics and ad operators, social media firms, and other data exchanges can identify you using this, and they can use this information for tracking what you say and do online.
Verizon has been in business with these companies to sell your identity to them -- Verizon is effectively including your name, address, Facebook account, and email address with every HTTP request you make. Again, this applies across all browsers and devices, and you cannot opt-out.
In some sense it's a bug in client software, that allows information to be stored for eventual inclusion in future requests (i.e., like a regular browser cookie), but outside the ability of the user to monitor or delete (unlike a regular cookie). For some time people mostly blamed this on Flash, but there are probably other ways for old and/or strangely-configured clients to screw up like this.
