Psoriasis is a chronic, inflammatory, T cell-mediated auto-immune disease mainly affecting skin and joints. It is a multisystem disease associated with a multitude of co-morbidities and thus, has become increasingly important for all medical fields, beyond dermatology and rheumatology. Psoriasis has also become more and more important as a model disease for scientist working on chronic inflammation and autoimmunity. And psoriasis has become increasingly relevant as a first-choice disease for proof of concept studies investigating the efficacy of newer pathogenesis-based treatments.