  We describe the Stagger Code for simulations of magneto-hydrodynamic (MHD)
systems. This is a modular code with a variety of physics modules that will let
the user run simulations of deep stellar atmospheres, sunspot formation,
stellar chromospheres and coronae, proto-stellar disks, star formation from
giant molecular clouds and even galaxy formation. The Stagger Code is
efficiently and highly parallelizable, enabling such simulations with large
ranges of both spatial and temporal scales. We, describe the methodology of the
code, and present the most important of the physics modules, as well as its
input and output variables. We show results of a number of standard MHD tests
to enable comparison with other, similar codes. In addition, we provide an
overview of tests that have been carried out against solar observations,
ranging from spectral line shapes, spectral flux distribution, limb darkening,
intensity and velocity distributions of granulation, to seismic power-spectra
and the excitation of p modes. The Stagger Code has proven to be a high
fidelity code with a large range of uses.
