Applications complete the installation of the operational system on the machine and the basic management and use of the machine :

video and Audio with VLC, FFMPEG, ALSA or PULSEAUDIO

virtual environments like VIRTUALBOX ou VMware,

that allow you to install proprietary applications that you can not do without, such as personal finance management,

netwoks and servers , Apache, DHCP, DNS, FTP, SSH                                                                              

security systems to prevent attacks or breakdowns