The D-ITP is a consortium of theoretical physicists from Amsterdam, Leiden and Utrecht. The initiative received an enormous boost with the award of a grant worth 18.3 million euros from the Netherlands Organisation for Scientific Research (NWO) as part of its 'Gravitation Program’. The research program of the D-ITP is based on three themes: cosmological matter, quantum matter, and topological matter. For each theme, a compact set of challenges is described and parallel methods are identified. These methods emphasize the unity of theoretical physics, and at the same time allow us to introduce novel mathematical concepts and techniques in adjacent fields.