The purpose of this Hercules Specialised Course is to give the participants an introduction to high pressure research at large experimental facilities such as the synchrotron and the neutron reactor. The basic principles of SR and neutron techniques used to explore matter at extreme conditions of pressure and temperature will be illustrated. The school will also provide cross-disciplinary examples in a representative range of scientific areas, covering fundamental physics, earth and planetary science, chemistry and material science.  The lectures will cover both theoretical and experimental aspects for a non-expert audience. They will be complemented by tutorials and practicals at several ESRF and ILL beamlines and include  an  introduction to high pressure cell loading techniques.