Cyber warfare involves using computers and networks to attack and defend against enemies. It can include hacking, denial-of-service attacks, and data theft. Nation-states, terrorist groups, criminal organizations, and individual hackers can all engage in cyber warfare to disrupt operations, steal information, intimidate enemies, or cause economic damage. Defending against cyber warfare requires strong security measures, software updates, backup plans, and international cooperation, as attacks are difficult to trace due to internet anonymity and the global nature of the cyber domain.