martin clayman is professor for marketing at the codes room institute of technology in germany. together with a colleague, he's going to take a look at the digital traces. jessica and mark leave online and see which can be used for individualized ads. most options are the thing that you have on spectrum that you'd really have to invest a lot of time and energy to browse the internet anonymously. i think the average consumer doesn't quite well to stop the data from being collected or not to empty. jessica regularly check this news website. the page saves the so called cookies. small data packages are unique identifiers on her computer. we ask the marketing experts to take a closer look at the new site. these cookies contain data on jessica's preferred language and other personal settings. so far so good, but they also find so called 3rd party cookies symbolized by these triangles. these cookies enable companies to follow people who've visited the new site as they continue browsing the web because they are accessed by other sites as well. if jessica visits one of these pages, they recogniz