Facebook is testing technology to track where users hover their mouse cursors to introduce 'precision advertising'.

Facebook's analytics chief Ken Rudin told the Wall Street Journal that the 1.2 billion-person social network is also testing technology that will collect data on whether a user's newsfeed is visible on their mobile device.
The problem that websites, including Facebook, face these days when it comes to monitoring user behavior is that most people think government surveillance – particularly with regard to the National Security Agency (NSA).
Officials with Facebook are not thinking that way – or so they say.
“These experiments look at aggregate trends in how people interact with the site to inform future product decisions,” the Facebook spokesperson said. “We do not share this information with anyone outside of Facebook and we are not using this information to target ads.”
Only time will tell if this type of technology will see the light of day on Facebook, but ithe social media group is not pioneering it.
Shutterstock, a stock photography agency, records everything people do on its site, including how long a cursor hovers over an image before the picture is purchased.
“Today, we are looking at every move a user makes, in order to optimize the Shutterstock experience,” CEO Jon Oringer told the Wall Street Journal in March. “All these new technologies can process that.”
One of those technologies used was Apache's Hadoop which Facebook already uses.