Snapchat is a popular mobile app that allows you to send videos and pictures, and send messages as well. A user can capture a photo or brief video, then add a caption or doodle or filter/lense, and send the finished creation (called a snap) to another user. You can also add your snap to your "story," a 24-hour collection of all your snaps broadcasted to the world or just to your followers. Additionally, the snaps disappear after a specified period of time.