Today at a press event in New York, Instagram founder Kevin Systrom has announced that the photo-sharing service is introducing private photo-sharing and messaging. The feature is called Instagram Direct. Instagram has always been a mostly public social network, with a broadcast structure instead of connections based on mutual friendship, like Facebook. The introduction of Instagram Direct marks a new phase for the company. Now, users who follow each other will be able to send each other private chat-like messages, which can include photos or videos (of course). Previously, users have only been able to like or publicly comment on pictures.