Snapchat is a photo messaging app developed by Stanford students that allows users to take photos or videos and send them to others for a limited time before they are deleted. Users can add text or drawings and choose how long recipients can view their snaps, from 1 to 10 seconds, before the content disappears from the recipient's device and server. With 350 million snaps sent per day, Snapchat has become popular among iPhone users and is working on monetizing features through in-app purchases and advertising.