A review is given of accelerators and colliding-beam installations operating at center-of-mass energies between 7 GeV and about 50 TeV. The basic principles underlying the design of such systems and ways of increasing the energy and intensity of accelerated-particle beams are briefly discussed. The scale of modern machines is illustrated by considering the examples of the proton synchrotron at the Institute of High Energy Physics at Serpukhov, the accelerating and storage complex at CERN, the accelerators at the Fermi National Accelerator Laboratory in the USA, the electron-positron storage complex in Hamburg, and the Stanford Linear Accelerator in the USA.