Please explain in simple terms how it is if I look at something online in another tab then come back to AB then adverts for what I was looking at appear at the top and sides? I use IE. I'm not bothered but it is a bit spooky.
Tracking cookies. Teeny tiny files of information that are stored in your browser cache from a website. When you look at another site, the browser uses the cookies to show you specific targeted adverts.
I find it spooky too, but agree they do track what you have looked at. They are all trying to sell you something. Mostly harmless but BT FON mucked up my pc so I tend not to click on them: if interested I go to the actual website first, not straight to the link.