GDN (Google Display Network):
The Google Display Network is a large network of websites that let you place display ads. In fact, that network is so large that it’s made up of over 2 million websites and reaches over 90% of Internet users globally. When thinking of display ads, you may be thinking of these annoyingly loud pop up adverts on your favourite news site, or these in-app interstitial ads where you have to wait 30 seconds before you can exit. Granted, they are display ads, however, there are so many more formats you can use to leverage display advertising without being intrusive and without hindering user experience.