This means different things to different people.  The first and foremost principle is the protection of human life.  After that, it is in the eye of the beholder.  To me, we have the foundations of Confidentiality, Integrity and Availability...

This is my product that I support at Microsoft.  Affectionately known as TMG, this is a very good firewall product for those out there looking for a solution that will integrate a proxy, secure publishing and IDS/IPS system into one complete package...