Knoppix is a Live Linux CD, is a Live Linux CD, is a Live Linux CD!
Live Linux CD means that the computer boots and runs completely from CD. Nothing is installed on your hard drive in order for you to experience many of the Open Source software packages available.

Knoppix is not a Linux distribution like for example Debian, openSUSE, Ubuntu or others.

Knoppix
  • cannot be upgraded (if you try it, you'll get chaos)
  • offers no updates or security updates
  • has no user management
  • has no password protection
  • is not designed for installation of not Debian packages
  • causes difficulties while you try to install Debian packages
  • requires experience with apt-get/aptitude whenever you want to change something