An online advertising company can re-create the history of a person’s Web browsing history using Verizon’s tracking system. The Electronic Frontier Foundation has published a list of tools that can block online advertising companies from collecting web browsing data. Verizon tracks its mobile subscribers’ web surfing by tagging their traffic at the carrier level with a number called a Unique Identifier Header. The type of tracking, known as “header enrichment,” is controversial. AT&T stopped using the method last year after running tests, ProPublica reported.”]