CMS Made Simple has only some basic features that belong to the standard installation. Any additional functionality can be installed with other modules. Think of CMS Made Simple modules as Lego bricks. Modules can be installed in any combination you choose. Some modules are combinable with or even dependant on other modules. Modules are additional features that anyone can put on their website.
To choose and install new modules, click on Extensions | Module Manager in the admin console. Notice that the modules listed here are not standard modules of CMS Made Simple and therefore not all of them are of the same high quality as the core modules. That is why you see the message "Use at Your Own Risk" above the list of modules. Nevertheless, there are many modules which are very useful, sophisticated, and were thoroughly tested by their developers.
The Available Modules tab facilitates the installation of packages you already know about. The modules are sorted...