IC

In roleplaying games, it means In Character. You can do whatever you want to, and If anyone says anything, you can just answer "Hey, don't take it seriously, it was just IC". Which means that the Out Of Character you has nothing to do with whatever foolishness your character did.

Pretty convenient, neh?

Somewhat annoying way to convey the words I see. Often used on AOL.

In the Cyberpunk subgenre of science fiction, and in Shadowrun specifically, IC is short for Intrusion Countermeasures, and is pronounced (And usually written) as "ice."

IC is used to defend a system from attacks by hackers (Deckers, in Shadowrun and some other places) . There are many different kinds of IC, but they are usually broken down into three categories:

• White Ice: Totally benign defenses, such as firewalls and alarms.
• Grey Ice: Mildly harmful countermeasures, designed to nullify a hacker's intrusive abilities, by damaging or destroying his programs, and possibly his computer.
• Black Ice: Very harmful countermeasures, designed to physically harm or even kill the hacker. Although these are usually illegal, many megacorporations use Black Ice to defend high-security data and facilities.