Equilibrium statistical physics provides an extremely powerful, universal formalism that tells us how many-particle systems in thermal equilibrium behave, and how we can characterize their properties by only a few macroscopic quantities. However, most systems and processes found in nature are out of equilibrium. Think of any living organism, or directed transport in cells mediated by molecular motors. Often these systems consist of only a few entities and are so small that thermal fluctuations play a prominent role. It has been a vision from the early days of statistical mechanics to develop a theoretical description for such small non-equilibrium systems that is comparably powerful and universal as is equilibrium statistical physics. The aim of this program is to bring together the leading experts in (non-equilibrium) statistical physics to critically discuss and evaluate the latest developments towards a universal theory for non-equilibrium systems.