Traditionally, geologists focussed their research on the solid part of the subsurface. Increasingly geoscientists are aware of the role of fluids in the structural, sedimentological, mineral and (bio)geochemical evolution of the Earth’s crust. Geofluids research focusses on fluid-related processes on geological timescales. It includes a wide variety of research on physical and chemical aspects of subsurface fluids (groundwater, petroleum, and geothermal, magmatic and metamorphic waters) in the Earth’s crust, on microscopic to continental length scales.The significance of understanding fluid processes and, as a consequence, of geofluids research in exploration, use and sustainable management of natural resources (groundwater, oil, gas, geothermal energy, ore minerals and salt), storage of energy carriers and energy wastes, and prediction of natural geohazards and its consequences is increasingly recognised. The worldwide interest in – and understanding of – fluid flow in relation to various geological processes have advanced rapidly, especially since the early 1990’s (Bethke 1985, 1989; Doligez, 1987; Garven, 1985; Hubbert, 1953; Tóth, 1980, 1987; and since 1990: Al-Aasm et al., 2002; Bredehoeft & Norton, 1990; Dahlberg, 1994; Garven, 1995; Ingebritsen & Sanford, 1998; Jamtveit & Yardley, 1997; Law et al., 1998; Lerche & Thomsen, 1994; Mc- Caffrey et al., 1999; Mitchell & Grauls, 1998; Parnell, 1994, 1998; Pueyo et al., 2000;Van Balen, 1995;Verweij, 1993).The latest overview of geofluids research is presented in the Proceedings of the Geofluids IV: Fourth international conference on fluid evolution, migration and interaction in sedimentary basins and orogenic belts (Verweij et al. 2003). These concepts, theories and methods pertaining to fluid flow in relation to various geological processes in different sedimentary basins have been very valuable for the research in onshore and offshore Netherlands