  Since the initial development of charged particle colliders in the middle of
the 20th century, these advanced scientific instruments have been at the
forefront of scientific discoveries in high energy physics. Collider
accelerator technology and beam physics have progressed immensely and modern
facilities now operate at energies and luminosities many orders of magnitude
greater than the pioneering colliders of the early 1960s. In addition, the
field of colliders remains extremely dynamic and continues to develop many
innovative approaches. Indeed, several novel concepts are currently being
considered for designing and constructing even more powerful future colliders.
In this paper, we first review the colliding beam method and the history of
colliders, and then present the major achievements of operational machines and
the key features of near-term collider projects that are currently under
development. We conclude with an analysis of numerous proposals and studies for
far-future colliders. The evaluation of their respective potentials reveals
tantalizing prospects for further significant breakthroughs in the collider
field.
