This section describes the global computing environment required for installing the Geant4 toolkit. To set up your specific computing environment for Geant4, refer to Section 2 of this Guide. A shell script (Configure) is provided to facilitate the installation procedure, and to help the user set up the environment correctly. Geant4 is supported under the following operating systems: Linux on PC with g++ (gcc compiler) MacOSX with g++ (gcc compiler) Windows/XP with MicroSoft Visual C++ Currently, this is the set of flavors which can be associated with the environment variable $G4SYSTEM to identify the system architecture and compiler used: Linux - Scientific Linux CERN, SLC4 (or SLC5) g++ gcc 3.4.6 (or 4.1.2) G4SYSTEM: Linux-g++ MacOSX - MacOSX Darwin 10.5 g++ gcc 4.0.1 G4SYSTEM: Darwin-g++ Windows - Windows XP and Cygwin32 MSVC++ 9.0, Visual Studio 2008 G4SYSTEM: WIN32-VC For a more detailed description of supported platforms/compilers and versions of third party software, please refer to the release notes available with the current release you're using in geant4/ReleaseNotes (also accessible from the web distribution page ). To run Geant4, the following software must be properly installed in your computing environment: C++ compiler (compiler from Unix vendor, g++ or Visual C++ for Windows systems) CLHEP library (see CLHEP reference guide cern.ch/clhep/manual/RefGuide ) GNU Make (note: g++ preprocessing is used to build file dependencies) is also used and a UNIX shell The Geant4 toolkit source code The above list of software is the minimum required for a non-graphical setup of Geant4. To use visualization graphics in Geant4 and/or a graphical user interface (GUI), at least one of the following graphic systems or packages is required in your computing environment: X Windows OpenGL or MesaGL (free software compatible with OpenGL) DAWN , a PostScript renderer Qt , a powerfull toolkit Open Inventor (free software from SGI) Open Scientist (Interactive environment, including GUI) HepRApp Browser ( HepRep Browser) WIRED4 JAS Plug-In ( HepRep Browser) Momo (a Java -based GUI environment, GGE, GPE, ...) VRML browser Alternatively, you can produce an ascii file for VRML or DAWN. More information is available in Section 8.6, Visualization Drivers, of the User's Guide for Application Developers. Histogramming facilities are provided through the AIDA abstract interface, which in this case needs to be installed as well: AIDA (Abstract Interfaces for Data Analysis) External, AIDA-compliant packages which provide the necessary functionalities for doing histogramming (and therefore, should be optionally installed) are: iAIDA (iAIDA, an implementation of AIDA in C++) JAS (Java Analysis Studio) Open Scientist (Interactive Analysis Environment). rAIDA (rAIDA, a Root implementation of AIDA)