Diffusion of information has never been quite an exciting topic nowadays, especially in the context of crypto. Underlying the blockchain technology, a network of users and nodes is built into a peer-to-peer configuration, through which cash flows, list of transactions, news, etc., are diffused throughout the connected universe.This book has the ambition to found the mathematical approach for describing the process of diffusion of information on a peer-to-peer network. Modelling such network by means of Graph Theory, we derive the diffusion equation, and solve it in the most general undirected and directed frameworks. Boundary conditions as well as delays, both essential for the technology description, are addressed, and numerical illustrations are shown throughout the book.This text is made for the reader eager to discover the essential support for the information communication inside the blockchain technology.