Most people have experienced this internet phenomenon: you look at a certain product online and suddenly every website is suggesting the same product to you. It’s what’s known as personalised advertising. “These are ads that have a reference to who we are, what we have looked at and used,” explains Rebekka Weiss from the German IT industry association Bitkom. Websites use tracking mechanisms to store what you look at. Mostly this is done using cookies, small files that the browser stores on your computer. “Web servers can have the browser set a cookie when the visitor accesses one of their pag…