In-feed ad unit adoption is growing across publisher sites with different ad unit types introduced and/or retired quickly,” said the IAB’s Susan Borst. “In addition, feed types are also evolving beyond the three main types (content, social and product), to mixed feed types that have variable aesthetics/content which don’t fall clearly into one bucket. But even with these changes over time, it is important that one thing remain the same and that is the need to evaluate the in-feed ads from the consumer perspective to ensure that they remain native, meaning that they are so cohesive with the page content, assimilated into the design, and consistent with the platform behavior that the viewer simply feels that they belong.”

They have a helpful infographic on this as well, which you can see here.

http://www.webpronews.com/infographic-looks-at-the-science-of-native-ads-2015-08