Approximately four years after its launch, Pinterest finally started formally selling advertising on its site. The step was significant, because ad sales often represent the primary means for social media sites to earn substantial revenues. The initial advertisements reportedly sold for about $1 million each and featured such well-known names as The Gap and Kraft.

But for Pintrest to ensure a steady stream of brands willing to fork over millions to have their advertisements placed next to a member’s fabulous causal fashion or clever meal idea boards, it needs to provide more than just surface-level connections. That is, it may make sense for The Gap to place advertisements on fashion-oriented boards, but it also wants to be able to track whether visitors to those boards prefer chinos from The Gap, sweaters from Banana Republic, jeans from Old Navy—or more problematically, entire outfits from its competitors.

In response, Pintrest has opened an application programming interface (API) that enables third-party developers to design marketing software to track the performance of specific, individual pins across the entire network. Similar software already running on other social media sites reveals how it might work on Pintrest: Brands can implement the software to determine whether one of their products is more popular than others, learn which product photos prompt the most shares and likes, and discern whether particular pins drive traffic to their own sites or even sales. With this information, the brand can adjust the pictures it uses on its own website to ensure the most popular, influential images are maximizing the company’s appeal to consumers.

The move is not unprecedented in social media, and observers even had been predicting it, ever since Pintrest hired away a former Facebook marketing developer to manage its own interests. Yet Pintrest’s approximately 30 million members represent a unique and specific group of online media users, such that this move should have implications particular to the still growing site.

Source: Cotton Delo, “Pintrest Unveils New Tech to Become More Measureable for Brands,” Advertising Age, May 20, 2014, http://adage.com