  We present Phantom, a fast, parallel, modular and low-memory smoothed
particle hydrodynamics and magnetohydrodynamics code developed over the last
decade for astrophysical applications in three dimensions. The code has been
developed with a focus on stellar, galactic, planetary and high energy
astrophysics and has already been used widely for studies of accretion discs
and turbulence, from the birth of planets to how black holes accrete. Here we
describe and test the core algorithms as well as modules for
magnetohydrodynamics, self-gravity, sink particles, H_2 chemistry, dust-gas
mixtures, physical viscosity, external forces including numerous galactic
potentials as well as implementations of Lense-Thirring precession,
Poynting-Robertson drag and stochastic turbulent driving. Phantom is hereby
made publicly available.
