If there’s one thing the App Store is saturated with, it’s messengers: WhatsApp, of course, but also Facebook’s, and Snapchat, and Hangouts, and Line, and Kik, and all the rest. So why would Pinterest, a social network for exploring your interests, spend time building a messenger? The answer says a lot about where Pinterest is going — and the product itself is one of the best things we’ve seen from Pinterest to date. In part, Pinterest messages simply closed the loop that the company started when they introduced the ability to send pins to your friends on the network last year. Today, Pinterest users send 2 million pins a day on the service. But to date there has been no native way of responding to the pins, short of sending your friend or co-worker an email. That’s where Pinterest messages come in.