Explanation:
A worm is a type of self-replicating malware that spreads autonomously across networks without the need for a host program. Unlike viruses, worms do not require user interaction to propagate.

Worms exploit vulnerabilities in network protocols and operating systems to spread rapidly across connected devices. They often cause network congestion, system slowdowns, and unauthorized data access.

Some worms deliver payloads that include backdoors, ransomware, or spyware. The sheer volume of traffic generated by worms can lead to system crashes and network failures.

Additional Information:
The Morris Worm (1988) was one of the first major worm incidents and caused significant disruption. Modern worms like Conficker continue to target unpatched systems.

Preventive measures include regular software updates, the use of firewalls, and network intrusion detection systems (NIDS). Security best practices such as least privilege access also reduce exposure to worm attacks.

Formal Definition:
A worm is a type of self-replicating malware that spreads independently across networks, exploiting system vulnerabilities without the need for a host file or user interaction.