Amir Efrati reports:
Internet users tap Facebook Inc.’s “Like” and Twitter Inc.’s “Tweet” buttons to share content with friends. But these tools also let their makers collect data about the websites people are visiting.
These so-called social widgets, which appear atop stories on news sites or alongside products on retail sites, notify Facebook and Twitter that a person visited those sites even when users don’t click on the buttons, according to a study done for The Wall Street Journal.
Read more in the Wall Street Journal