Designing diagrams, a graphics’ semiotic is a theoretical essay written for Emilio Patuzzos master degree in communication design at the Politecnico di Milano. The thesis aims to provide a new method to approach the more and more popular discipline of visualising data by promoting a new semiotic-based method to design such “artefacts”. Within a two year research the book was mainly inspired and based by the great thinkers’ theories: Umberto Eco, Rudolf Arnheim, Louis Hjelmslev, Roman Jakobson, Roland Barthes, Charles Peirce, Dan Sperber, Deirdre Wilson, Jacques Bertin and many others. By reinterpreting these reflections and thoughts about semiotic, linguistic and design, I structured the “Design del diagramma”. The design of the book was kept very simple to encourage reading and to avoid any distraction. The upper part of each page reports information about the current paragraph, chapter and section, providing an intuitive tool to discover the thesis. The red-plastic package was made to prevent any damage to the book when shipped to all people who supported me in this work. The format was inspired by the Einaudi PBL’s series, a work I’ve always looked up to as a symbol of good design and as a symbol of the spreading knowledge at fair prices.