What are Supercookies and how Verizon users will be able to opt out from being tracked

Verizon will allow users to turn off Unique Identifier Headers (aka Supercookies) tracking, after complaints from privacy advocates

A so-called "supercookie" is a cookie with an origin of a top-level domain (such as .com). An attacker in control of a malicious website could set a supercookie and impersonate legitimate user requests to another website that shares the same top-level domain (such as .com) as the malicious website. Unlike regular cookies that are quite easy to remove from browsers, "supercookies" are very hard to remove. For that reason privacy advocates have been raising hell since the existence of supercookies came to light. Supercookies can in fact follow the websites you visit and track all your online activity, including every visited link, mainly for the purpose of collecting data for advertisers.
Following the public outcry over supercookies, Verizon now says that it will give users the ability to shut down supercookies altogether. "We have begun working to expand the opt-out to include the identifier referred to as the UIDH, and expect that to be available soon," said Debra Lewis, a spokeswoman for Verizon. UIDH is just another name for supercookies, and stands for "Unique IDentifier Headers". The carrier also said that they do not use UIDH to share any browsing activity with advertisers, or to collect web browsing information for other purposes.