This session will focus on key aspects of relaxation relevant for the glass transition. Experimental, modeling, and theoretical developments will be considered. The topics include: Structural relaxation, viscosity and fragility; dynamic heterogeneities; new algorithms for modeling, rigidity, pressure and damage effects. All glass systems including oxides, metallic glasses, organic glasses and chalcogenides will be covered. Contributions from other systems that share the same phenomenology like granular matter, colloids and jammed systems are also welcome.