Cyberspace: The widest possible digital realm, the electronic universe that includes not only the Internet, but also computers unconnected to it, such as classified military and other nonpublic business as well as industrial systems.
Stuxnet: The world's first publicly identified "cyber superweapon," software designed not just to destroy data, but also to invade a network and change the instructions to a computer-controlled industrial process, resulting in the destruction or malfunction of equipment. In this case it was a "digital missile" that, experts say, was designed to target an Iranian nuclear-fuel refining facility, damaging or destroying at least 1,000 centrifuges.
Rootkit: Unauthorized software installed by an intruder on a computer network that allows the invader to take full control of the system while its presence remains hidden. The term "root" refers to a privileged account with full access to run the network.
TrapDoor: Software program added to a computer by an intruder that allows unauthorized reaccess to the system at a later time. It's also called a "Trojan" program after the Trojan horse of Greek mythology – pretending to do one thing while doing another.
Logic Bomb: Malicious software designed to erase, destroy, or disable a computer system. Weaponized versions, like Stuxnet, are designed to wreck machinery and may cause explosions and other malfunctions in industrial equipment.