Snapchat is a mobile app that allows users to send photos, videos, and messages that disappear after being viewed. The document summarizes Snapchat's key features and statistics on its growing user base. It also provides examples of how brands are using Snapchat to engage younger audiences through temporary promotions, discounts and sponsored content. While Snapchat offers new opportunities for creative advertising, the platform also poses challenges for brands in building large followings and measuring engagement.