An anonymous reader quotes a report from Motherboard: The idea of websites tracking users isn't new, but research from Princeton University released last week indicates that online tracking is far more invasive than most users understand. In the first installment of a series titled "No Boundaries," three researchers from Princeton's Center for Information Technology Policy (CITP) explain how third-party scripts that run on many of the world's most popular websites track your every keystroke and then send that information to a third-party server. Some highly-trafficked sites run software that records every time you click and every word you type. If you go to a website, begin to fill out a form, and then abandon it, every letter you entered in is still recorded, according to the researchers' findings. If you accidentally paste something into a form that was copied to your clipboard, it's also recorded. These scripts, or bits of code that websites run, are called "session replay" scripts. Session replay scripts are used by companies to gain insight into how their customers are using their sites and to identify confusing webpages. But the scripts don't just aggregate general statistics, they record and are capable of playing back individual browsing sessions. The scripts don't run on every page, but are often placed on pages where users input sensitive information, like passwords and medical conditions. Most troubling is that the information session replay scripts collect can't "reasonably be expected to be kept anonymous," according to the researchers.