ICE

ICE (Intrusion Countermeasure Electronics) is a cybernetic protection system installed in any network to prevent intrusion and tampering by unwanted parties. In visual cyberspace, it manifests as a large crystalline shield. Its color denotes its strength, and other traits assigned to it are secondary properties that can be read by the public.

Colors
ICE strength increases along the rainbow from red to violet; white and black are also types of ICE and are different than most.
 * White: basic shielding offered by any public terminal or home interface. Only the poorest of the poor have no ICE, as it takes a homebrew system to lack even basic white protection. Any real hacker can smash it, but it keeps the thugs on the cyber-street out. It's an eggshell of protection.
 * Red: nontrivial personal protection and basic home network shielding. Used also in public schools, libraries, etc. -- places suited to widespread use who want a litlte more security. Any public terminal will offer red-level protection to its subscribers who pay for the service. Too basic for secondary traits, it's just a thick layer of armor.
 * Orange: higher-level shielding commonly found in small companies, common gambling dens, bookie nets, private schools, most universities, and common infrastructure organizations like utilities and trade. Orange is the first level to have secondary traits. Personal ICE colors usually stop here.
 * Yellow: research labs, high-end universities, mid-range companies, personnel tracking servers, data backup servers. Commonly loaded with high-rate data transfer trait, so that it can eject data from its guarded server and clear the server before hackers get their hands on it.
 * Green: basic government work, stock market, high-level finance, police systems, etc. Scary things.
 * Blue: Heavy, flashy corporate and government shielding. This is the public ICE seen around very high-security nodes and is meant to deter intrusion by sheer appearance alone. It usually carries several secondary traits also heavily advertised. Likened to a "Beware of Dog" sign with a huge wolf standing behind it, it has both bark and bite.
 * Violet: Megacorporation and government black ops under-ICE. Effectively invisible until approached, it is extremely nasty. It is so difficult to manage that it can only be created in thin layers; otherwise, it tends to screw up anything it touches. It is usually loaded with secondary traits and will destroy a hacker upon a failed cracking attempt. Any contact with it triggers hordes of alarm systems and watchdogs, and may induce a self-destruct if knowingly pierced.
 * Black: Considered by most to be a rumor of the "None have seen this and lived" sense. It is thought to be some kind of mythical hacker's supershield, a defense that can never be broken bause it is likened to a perfect brain-machine merging. Just as it is impossible to truly comprehend and probe the depths of the human mind and soul, it is impossible to unravel black ICE, as it is entangled in the mind itself. If black ICE were to exist, behind it would be a naked sentient mind.