Traffic is called “Dark Social”, which is not comprehensible for analytics applications. This category includes, for example, content that is shared via emails or messenger. The term was introduced in 2012 by Alexis C. Madrigal, journalist at the magazine “The Atlantic”. At the time, Madrigal complained in an article that over 56 percent of all page views at Theatlantic.com would come from non -measurable sources. the study " The Dark Side of Mobile Sharing " is now making 82 of the mobile shares. “Dark Social” is a big problem for analysts, advertisers and companies. Because this traffic is usually particularly valuable because personal recommendations are often made here.