To identify what personal information gets passed to other companies when you log in to popular websites, The Wall Street Journal tested 50 of the top sites (by U.S. traffic) that offer registration, excluding sites that required a real-world account, such as banking sites. The Journal also tested 20 selected other sites that focus on sensitive subjects such as dating, politics, health, or children’s issues, and our own site, WSJ.com. Click here to read more about the methodology. Results for each site are below. Sites are ranked by popularity, based on comScore's numbers. Sites not in comScore's top 1,000 are marked with a "*".