Over the last 50 years increasingly large and more sophisticated devices have been designed and put into operation, for the study of particle and nuclear physics, magnetic confinement of high temperature plasmas for thermonuclear fusion research, and gravity wave observatories based on laser interferometers. The evolution of these devices has generated many developments in ultrahigh and extreme high vacuum technology that were required for these devices to meet their operational goals. The technologies that were developed included unique ultrahigh vacuum vessel structures, ultrahigh vacuum compatible materials, surface conditioning techniques, specialized vacuum pumps, and vacuum diagnostics. Associated with these technological developments are scientific advancements in the understanding of outgassing,limits of UHV-compatible materials and particle-induced desorption effects. (C) 2003 American Vacuum Society.