I will present an overview of recent developments in source detection and estimation in randomly growing graphs and diffusions on graphs. Can one detect the influence of the initial seed graph? How good are root-finding algorithms? Can one engineer messaging protocols that hide the source of a rumor? I will explore such questions in the talk. This is based on joint works with Sebastien Bubeck, Ronen Eldan, Elchanan Mossel, Jacob Richey, and Tselil Schramm.