Our Library system has an Instagram account. There are a lot of standardized guidelines on how we must tag and caption images at HCL. Instagram is like the Twitter of photo sharing.
I reviewed the Snapchat tutorials but did not make an account because I don't think I will use it. My teenagers are probably on Snapchat. Photos disappear after a few seconds after viewing, unless it is saved as a story, in which case they are viewable for 24 hours. This may give a false sense of security, because there are apps that can save the image, or someone can take a screenshot. More secure options are Wickr and Silent Circle.