# Install LAMMPS

You can download LAMMPS as an executable or as source code.

When downloading the LAMMPS source code, you also have to [build
LAMMPS](Build). But you have more flexibility as to what features to
include or exclude in the build. When you download and install
pre-compiled LAMMPS executables, you are limited to install which
version of LAMMPS is available and which features are included of these
builds. If you plan to [modify or extend LAMMPS](Modify), then you
**must** build LAMMPS from the source code.

:::: note
::: title
Note
:::

If you have questions about the pre-compiled LAMMPS executables, you
need to contact the people preparing those executables. The LAMMPS
developers have no control over their choices of how they configure and
build their packages and when they update them.
::::

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::: {.toctree maxdepth="1"}
Install_linux Install_mac Install_windows Install_conda

Install_tarball Install_git
:::

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These are the files and subdirectories in the LAMMPS distribution:

  ------------- ---------------------------------------------
  README        Short description of the LAMMPS package

  LICENSE       GNU General Public License (GPL)

  SECURITY.md   Security policy for the LAMMPS package

  bench         benchmark inputs

  cmake         CMake build files

  doc           documentation and tools to build the manual

  examples      example input files

  fortran       Fortran module for LAMMPS library interface

  lib           additional provided or external libraries

  potentials    selected interatomic potential files

  python        Python module for LAMMPS library interface

  src           LAMMPS source files

  tools         pre- and post-processing tools

  unittest      source code and inputs for testing LAMMPS
  ------------- ---------------------------------------------

You will have all of these if you downloaded the LAMMPS source code. You
will have only some of them if you downloaded executables, as explained
on the pages listed above.