Dive summary: 

• Responsive ads are gaining popularity as a way to deal with the increase in mobile viewing. 
• Rather than purchase a different ad for each type of device, a responsive ad adjusts to whatever screen size it is being viewed on, whether that be a 27-inch desktop monitor or an iPhone. 
• Say Media is a front-runner in the development of these responsive ads; their goal being to create something that fits in more natural in the feed of a device rather than a traditional banner ad. 

From the article: 

"As publishers across the board see more of their traffic coming from mobile devices, it’s now crucially important they find ways to better generate more revenue from those audiences. Whether that’s achieved through responsive ad units or things like sponsored content remains to be seen, but it appears that publishers relying on IAB standard banner ads are unlikely to ever see the influx of brand dollars many have predicted over the years."