Display advertising in the US will grow by 70% by 2021, according to a study by Forrester Research. The study predicts that the majority of this growth will be driven by social media, mobile and video advertising. Looking at social media advertising, Facebook is set to see the biggest rise in display advertising. Looking at mobile advertising, the majority of this growth is expected to come from in-app video ads. There is also set to be an increase in marketers seeking out specific, high quality websites on which to advertise, in order to control fraud and to ensure that they appear in a “brand-safe” environment. The latter prediction probably stems from controversy that took place earlier this year, when several major brands discovered that their ads were appearing on extremist and illegal videos on YouTube.