Jonathan Mayer writes:
Click the local Home Depot ad and your email address gets handed to a dozen companies monitoring you. Your web browsing, past, present, and future, is now associated with your identity. Swap photos with friends on Photobucket and clue a couple dozen more into your username. Keep tabs on your favorite teams with Bleacher Report and you pass your full name to a dozen again. This isn’t a 1984-esque scaremongering hypothetical. This is what’s happening today.
Stanford conducted an important web leakage study to assess its pervasiveness, summarized in the blog post. Of note, Jonathan notes the implications:
From a legal perspective, identifying information leakage is a debacle. Many first-party websites make what would appear to be incorrect, or at minimum misleading, representations about not sharing PII.
Read more about the study’s methodology and results on CIS.