It has recently come to a head that Verizon Wireless uses permanent, undeleteable cookies to track their customer's mobile device usage and browsing habits, and then sells this information to advertisers.
This is neither a new concept, nor one unique to mobile service providers.
While in the light of consumer outrage, AT&T and Verizon are promising to systematically discontinue use of "supercookies," it is doubtful that they will stop tracking their customers' behaviors.
Home and business internet service providers also routinely track their customers' internet habits, though less so for marketing purposes and more for bandwidth abuse.
Customers of AT&T, Verizon, and other ISPs, or internet service providers, can have their incoming and outgoing data tracked through the use of port scanning and IP pings to measure and track their website activity even when using a secure internet browser.
Even those who use IP-blockers and VPNs, or virtual "tunnels," can be tracked, though it takes more effort.
Using any aspect of the internet carries a risk for some degree of someone tracking your activity. While most of the tracking is not malicious, it is still key to be aware of that such practices are common for any business or organization that provides internet-based services.
"Verizon Supercookies, Which Track Web Browsing, Blasted for Bogus Secruity, Privacy," by Jeff Stone, International Business Times. January 26, 2015 [link]
"Verizon's Perma-Cookie Is A Privacy-Killing Machine," by Robert McMillian, Wired. October 27, 2014 [link]
"How to Disable Facebook Cookies," by Tom Cheshire, Wired UK. December 19, 2011 [link]
"Is Your ISP Spying On You?," by Lincoln Spector, PCWorld. September 3, 2012 [link]