Particle accelerators and detectors have been initially developed for the study of particle physics, analogously as telescopes for astronomy and microscopes for biology. They have become the most complex and expensive scientific instruments ever built by mankind and exploit every aspect of today's cutting-edge technology. In many cases, accelerators have been the driving forces behind these new technologies. Today tens of thousands of accelerators exist worldwide and are used in different domains such as material science, biology, sterilization and polymerization, radiation surgery and cancer therapy, production of radioisotopes as tracers in medicine, and lithography for the fabrication of electronics components.