We all would like to think that the sites we visit the most respect our privacy and wouldn't share that information with other people. Unfortunately that is pretty much a pipe dream as even the most popular web sites on the Internet have been found to share just about everything you do with anyone who wants to know.
In a recent investigation of web site privacy policies, the Wall Street Journal tested 50 of the most popular web sites in the United States (including their own site and 20 additional sites in sensitive categories) to see how they treated the data of registered users. To pick the sites used in the investigation WSJ used data from a list of a 1,000 sites as compiled by ComScore in their June 2012 most popular listing.
The WSJ's methodology for their investigation was based on techniques used by researchers at AT&T Labs and Worchester Polytechnic Institute. For each of the sites in the list WSJ created a new account, entering name, username, email address, birth date, location, password, and any other "required" information that was a part of the site's registration process.
After completing registration the Journal would log out, then log back in and browse all the known pages for the site in question, and then after logging out again they would totally clear the browser cache of all cookies before continuing on to the next.
The following is a list of the top 20 and the type of data that they shared with others.
First this is the color coding of the type of data shared:
Here is the listing with the information explanation of about what Yahoo sends – you can see more on the Wall Street Journal page and drill down for the names on the list to see what they share as well.