This week was an exciting one for east coasters like ourselves. Instagram hit a major milestone of 400 million users. Pinterest launched its API out of beta. And of course, the Pope came to town. Let’s take a look at this—and more—in depth.

1. Pope Francis’ digital and social reach helps put him in your pocket.

Christian media company Aleteia USA is reaching out to younger Catholics during Pope Francis’ U.S. visit with a large social media campaign. It is a multi-platform approach that goes by the handle @PopeIsHope.

2. Instagram and Twitter welcome #PopeFrancis with hashtags and emoticons.

Ever since the Pope touched down in the United States, his historic visit has been trending on social media. Platforms like Instagram, Snapchat and Twitter have been having fun with it, with Pope-themed emoticons, geotags and hashtags.

3. Instagram hits 400 million users.

“It took nine months for the photo-sharing app to tack on its latest 100 million regular users. In that time, Instagram added notable celebrities such as the soccer star David Beckham and Caitlyn Jenner, who recently received the Arthur Ashe Courage Award at ESPN’s annual awards show.”

4. Pinterest crosses user milestone of 100 million.

Pinterest has hit 100 million users, and still has plenty of room for advertising growth. In the last year or so, Pinterest has deepened its push into advertising, pitching itself to big brands and marketers as an avenue to promote their products.

5. Redefining ‘user engagement’ on Instagram and other social channels.

The New York Times explores the legality of UGC, highlighting a case in which Crocs ‘creeped out’ a fan by regramming without permission.

6. Pinterest says pinners are already planning for the holidays.

“Pinterest says people are already searching for and pinning creative gift sets and stocking stuffers. It cited a study by market researcher CivicScience that found 47% of Pinterest users start their holiday shopping before Thanksgiving (compared to 39% of the population overall).”

7. Why Instagram is the future of mobile and social commerce.

“According to Stephanie Trunzo, chief digital officer at the digital marketing agency PointSource, all signs point to the rise of socially enabled mobile commerce. And she pointed to the intimacy and immediacy of Instagram as a mobile-first platform as the biggest factor in the platform’s current and future success.”

8. Pinterest finally launches its full API out of beta.

“We’re excited to announce that our API is now open for development! Start building apps and integrations with Pinterest to help people discover, save and do more with your business.”

9. A look inside the platform that holds the future of image analytics for brands.

“There is something very deep about the human experience that is rooted with imagery and what’s fascinating about this is as people communicate more and more visually, the way that consumers learn about their world, about products, about experiences, about things that brands care about is through pictures.”

10. How to turn Instagram into a revenue channel.

While the shopper of today wants to take action on the inspirational images they see, many marketers are still striving for a way to turn short-lived Instagram images into instant revenue drivers. Here’s how.