The FLUKA code is a general purpose Monte Carlo code for the interaction and transport of hadrons, leptons, and photons from keV (with the exception of neutrons, tracked down to thermal energies) to cosmic ray energies in any material.

It has been built with the aim of including the best physics models in terms of completeness and precision, through a microscopic approach where each step has sound physics bases. Reliability is pursued by comparing with particle production data at single interaction level. No tuning on integral data, like calorimeter resolutions, thick target yields etc., is performed. Therefore, final predictions are obtained with minimal free parameters, fixed for all energies and target/projectile combinations. Results in complex problems as well as scaling laws and properties come out naturally from the underlying physics models and the basic conservation laws are fulfilled a priori. Moreover, the microscopic approach preserves correlations within interactions and among the particle shower components, and it provides predictions where no experimental data is available. Powerful biasing techniques are built-in to allow to critically reduce computing time when needed. Transport in magnetic field is also performed.

FLUKA has a wide range of applications, spanning accelerator design and shielding, radiation protection, particle physics, dosimetry, detector simulation, hadrontherapy.

The history of FLUKA goes back to 1962-1967, when J. Ranft was working at CERN on hadron cascades under the guide of H. Geibel and L. Hoffmann, and wrote the first high-energy Monte Carlo transport codes. Starting from those early pioneer attempts, one can distinguish three different generations of FLUKA codes along the years, which can be roughly identified as the FLUKA of the '70s (J. Ranft and J. Routti), the FLUKA of the '80s (P. Aarnio, A. Fassò, H.-J. Moehring, J. Ranft, G.R. Stevenson, and J.M. Zazula), and the modern FLUKA (A. Fassò, A. Ferrari, J. Ranft, and P.R. Sala, with contributions by G. Battistoni, F. Cerutti, M. Chin, T. Empl, M.V. Garzelli, M. Lantz, A. Mairani, S. Muraro, V. Patera, S. Roesler, G. Smirnov, F. Sommerer, and V. Vlachoudis). The latter has been distributed under joint CERN and INFN copyright from 2003 until 2019