A large number of real-life phenomena - spread through chemistry, ecology, and biology - can be mathematically described through diffusive systems such as reaction-diffusion systems with linear or nonlinear diffusion, nonlocal diffusion, and cross-diffusion systems. These systems are extremely interesting to investigate not only due to their importance in applications (reaction chemistry, population dynamics, collective phenomena in life sciences) but also because they give rise to a rich variety of complex behaviours, such as pattern formation and bifurcations. In the second edition of this School – which follows the 2021 online first edition – we aim to bring together experts from different communities to cover the investigation of diffusive systems from several viewpoints: analytically, combining methods and techniques from Partial Differential Equations (PDEs) and dynamical systems to derive and analyse mathematical models for the applied phenomena; numerically, reviewing the most recent techniques and software for the computation of bifurcation diagrams and continuation with respect to the systems’ parameters; and, last but not least, from the applied - in particular biological – viewpoint, since a constant exchange of knowledge between the theoretical investigations and the experimental data is crucial in advancing research in this area.