Snapchat launched in September 2011. There are now 100 million daily active users with 18% of all social media users using Snapchat. The average number of photos shared on the service is 9,000 snaps per second! There are 8 billion daily video views. Most of the Snapchat users are millennials (73%).
Techboomers led me to a guide for older adults to understanding what Snapchat is all about. You should know what your kids & grand-kids are using. In that article is a link to a short video describing Snapchat.