According to @eMarketer, @Pinterest is projected to have more than 47 million monthly active users in the US in 2015, and more than 50 million in 2016. While the social media site is growing, it still has much less activity than @facebook. Facebook reportedly had 128 million daily active users in the US two years ago (2013). This is also behind @twitter, which reportedly had 63 million monthly active users in the Q4 of 2014. eMarketer says that Pinterest could be a valuable tool for marketers because of the millions of people who use it are in a shopping mindset. Pinterest still has many things to accomplish before becoming a major player in the digital advertising word, like increasing its user base and filling out its ad product suite. Pinterest plans to add a “buy” button soon to compete with Facebook and Twitter in the social commerce market. - Link