The self-portrait is nothing new. Painters and photographers have always used themselves as subjects. Today, however, almost everyone walks around with a camera in his or her pocket. This is because most cell phones have cameras on them. The fact that most people have cell phone cameras with them all the time has led to the rise of the selfie. A selfie is a self-portrait usually taken with a cell phone. Since the pictures are usually taken on a cell phone, many people tend to share these photographs with friends and even strangers on different social networking websites. Some of the popular social networking platforms people use to share selfies include Instagram, Snapchat and Facebook. People usually take selfies when they are engaged in normal day-today activities. They take selfies of their commutes to work or school. People take selfies of themselves eating. Other people take selfies to show what they are wearing or whom they are hanging out with.

Which social networking platform is not mentioned in the passage?