Photo Sleuth is based on what is called a neural network. Its a computer program that has been trained with millions of photographs of birds to recognize their unique patterns. It works just like our brain works for recognizing patterns. Video  This video might help you understand how a neural network works. Its an interview with Bill Atkinson by Leo Laporte on Triangulation from August 24, 2018. Bill Atkinson invented HyperCard for the Macintosh, developed the Mac's QuickDraw routine