What is a destructive program that spreads from computer to computer called?

A destructive program that spreads from computer to computer is called a "virus." Viruses attach themselves to legitimate programs or files and can replicate themselves to infect other systems. They often cause harm by corrupting or deleting data, slowing down system performance, or even compromising security. Other similar types of malicious software include worms and Trojans, but viruses specifically require a host program to propagate.