  Through the last three decades, accurate simulation of the interactions of
particles with matter and modeling of detector geometries has proven to be of
critical importance to the success of the international high-energy physics
(HEP) experimental programs. For example, the detailed detector modeling and
accurate physics of the Geant4-based simulation software of the CMS and ATLAS
particle physics experiments at the European Center of Nuclear Research (CERN)
Large Hadron Collider (LHC) was a determinant factor for these collaborations
to deliver physics results of outstanding quality faster than any hadron
collider experiment ever before.
  This review article highlights the impact of detector simulation on particle
physics collider experiments. It presents numerous examples of the use of
simulation, from detector design and optimization, through software and
computing development and testing, to cases where the use of simulation samples
made a difference in the precision of the physics results and publication
turnaround, from data-taking to submission. It also presents estimates of the
cost and economic impact of simulation in the CMS experiment.
  Future experiments will collect orders of magnitude more data with
increasingly complex detectors, taxing heavily the performance of simulation
and reconstruction software. Consequently, exploring solutions to speed up
simulation and reconstruction software to satisfy the growing demand of
computing resources in a time of flat budgets is a matter that deserves
immediate attention. The article ends with a short discussion on the potential
solutions that are being considered, based on leveraging core count growth in
multicore machines, using new generation coprocessors, and re-engineering HEP
code for concurrency and parallel computing.
