Sphere is an iOS application built in 24 hours at AngelHack in New York City in 2013. Sphere allows users to create events at locations and then invite friends or the world to attend. Event goers can see all the events going on around them, see which of their Facebook friends are attending as well as the reviews given to that event allowing them to decide whether or not to go. Sphere uses geofencing so that the user doesn't even have to take their phone out of their pocket to sign in. Once they walk within the radius of the event, they automatically sign in and once they leave the event, they automatically sign out. If they're at the event they can then share reviews and ratings for their peers to see!