Disordered systems emerge from physical models by incorporating additional random effects. They also appear as models for complex systems in various contexts, such as computer science or biology. Understanding these models rigorously has been a great challenge for several decades, but the mathematical research in disordered systems and related fields has seen tremendous progress in recent years and benefits from a fruitful interplay of techniques from probability theory, mathematical analysis, combinatorics and mathematical physics. The aim of the school is to present to PhD students and young researchers some of the most fascinating developments in disordered systems and related fields in recent years.