Here's a Buyer's Guide to Ad Targeting on 8 Social Platforms 

 Since September, Instagram has extended its ads offerings from eight to 38 countries, added 30-second ads, debuted landscape images and introduced a premium format called Marquee. Also, it is pitching call-to-action buttons that offer political marketers and other fundraisers the ability to employ a "Donate Now" button.

http://www.adweek.com/news-gallery/technology/heres-buyers-guide-ad-targeting-8-social-platforms-167754