This is a type of computer virus that is responsible for copying itself. This is usually very bad for the computer that it will set itself on. There is a possibility that it will corrupt the system that it is on. There is even a possibility that it will start to delete vital files within the computer.
The reason why it is deadly is it is usually not detected early. It may be inside a large computer program that would not raise your suspicions. There are other types of viruses that can be downloaded on your computer. Having the right antivirus program will greatly help.
Traditionally, a computer virus is a line of code or a function within a larger computer program. While not all computer viruses are harmful, the most famous ones can cause a lot of damage.