XFCE Desktop Environment
Windows manager is an app which manages all the windows. Great definition, right? xfwm is the default and can be replaced by others like fluxbox or can be installed alone or even adjusted to work with other DEs.It has a terminal, libraries, cd burner and other projects which are more or less designed to be light on system resources and flexible on the configuration part. The most important project would be the Xfce settings manager. This provides so much configuration that new users sometimes feel confused. But it is useful for experienced users.