LMOD-QuickReference-Guide.md

-## First Steps
-
 The system now uses a combination of the LMOD module system and the EasyBuild automatic build framework. Although, largely compatible LMOD has some differences in usage and module names as documented below.
 
+## Basics
+
+LMOD uses a hierarchical module scheme, where not all modules are visible at any given time. You can list the module currently available with the `avail` option.
+
+```sh
+> module avail
+```
+
+You can load a module with the `load` option.
+
+```sh
+> module load foo
+```
+
+**Note:** *If no version is specified, the default version is automatically chosen. If only a single version is available of a certain module, then  this will automatically become the default. Default versions of modules are marked with `(D)` in the list of available modules.*
+
+When loading a module, the module system may set module-specific variables in the environment. This may influence the `PATH` and `LD_LIBRARY_PATH`, influencing executables and libraries visible to the user. To remove any modifications to the environment by a specific module, you can unload specific modules with the `unload` option.
+
+```sh
+> module unload foo
+```
+
+To unload all modules at once, you can `purge` the module environment, which unloads all loaded modules.
+
+```sh
+> module purge
+```
+
+To get a list of all loaded modules, you can use the `list` option.
+
+```sh
+> module list
+```
+
+If you don't know how a specific module is called or a module is currently not visible to you and you want search for a software, you can use the `spider` option.
+
+```sh
+> module spider
+```
+
+**Note:** *Searching for a module with `spider` is case in-sensitive and also returns partial matches (the search argument is part of an existing module). Further note that `spider` searches in the module name and the description.*
+
+To unload a module and load a module with one call, you can use the `switch` option.
+
+```sh
+> module switch foo bar
+```
+
+**NOTE:** *LMOD automatically unloads conflicting modules and inactivates modules that are no longer available.*
+
+```sh
+> module spider foo
+```
+
+When called with only with the module name and no specific version, the output of `spider` lists all available version across all toolchains. When called with a specific version, the output lists toolchains that will make it available.
+
+```sh
+> module spider foo/1.2.3
+```
+
 ### Core Compiler
 
-Some compiler
+For all packages a certain version of GCC is automatically loaded as `GCCcore` module. The `GCCcore` module will be part of the dependencies for making a certain module visible.
 
 ### Toolchains
 
 Toolchains are so-called meta modules that load a specific Compiler and MPI combination (and in some cases some additional libraries).
 
-
 #### Existing Toolchains
 
 ##### Intel-based