Final answer:
Malware is typically categorized into viruses, worms, and trojans, each with distinct characteristics and methods of spreading.
Step-by-step explanation:
In Chapter 9, malware is categorized into three common types, including viruses, worms, and trojans. Viruses are malicious code that require a host program to replicate, worms are standalone malware that replicate themselves to spread across networks, and trojans are disguised as legitimate software that carry malicious operations. Knowing these categories helps in understanding the dangers they pose and the measures that can be taken for protection.