1) "when a user clicks on a link, there is a clear visual cue that information is being
sent over the network – the target of the link will know that the user has clicked.
However, when we list clicking as being tracked covertly, we mean that there is an additional event-handler that tracks the click, and sends information about the click to another server. google is known for doing this: when a user clicks on a link on the search page, the click is recorded by google through an event handler, without any visual cue that this is happening"
2) Of the 115 sites on which the filtered flow were reported, we found that 7 used a behavior tracking software product developed by tynt to track what is copied off the sites.
3) "While investigating several sites that installed event handlers, we also found that the huffingtonpost site exhibits suspicious behavior."