A recent article published by the Electronic Frontier Foundation has brought to light some startling news. Verizon Wireless is modifying its users' traffic while on their network to insert a tracking code that allows websites to monitor your browsing habits regardless of your privacy or cookie settings on your computer, overriding end-user privacy settings. This tracking affects all browsing data through HTTP connections (regular web traffic), including application data. While Verizon claims to be using it to enhance advertising, it also opens the door to gross breaches in user privacy.
The header is nearly invisible and remains even if a user deletes all of their browsing data and cookies. The tracker is not optional or able to be disabled and even tracks users while in the 'Private Browsing' mode of their browser. It also bypasses several other privacy functions, such as 'Do Not Track' option on some devices.
The tracker only reads plain text and isn't able to read encrypted traffic so encrypting your connection is the only way to prevent the tracker from recording your data. You can use HTTPS, an encrypted proxy, Tor, or a VPN service like GoTrusted. Only a VPN or Tor will provide full protection in this case.
The news doesn't stop with Verizon. AT&T has said they are also testing a similar tracker for use on its networks and you can likely expect other carriers to follow suit.