Writing on the Wall is an anonymous, anti-centralization social networking tool. There is no sign up, there are no usernames, and nothing can be traced back to your phone. Your mark is comprised of your location, your message, and the time you leave it. You can leave a message at any location in the world, but only while youre there. In turn, you can see messages that others have left within one city block of your current location. All messages have a life of two weeks.