A PC Computer virus is a software program that is secretly introduces itself into your PC Desktop Computer or Laptop Computer system. Viruses usually operate without the knowledge or desire of the PC Desktop Computer or Laptop Computer user. Viruses are often hidden in other programs or documents and when opened, the virus gets loose. One particular aspect of the virus is its capability to spread itself from one PC Desktop Computer to another by replicating and attaching itself to another program or file.
Viruses have the capability of infecting any type of files. Files usually attacked are .com, .exe, .sys, .bin, .pif or any data files, such as word or excel.
The virus code must be executed in order to have any effect. This means that the virus may exist on your PC Desktop or Laptop Computer without infecting your system. The PC Desktop or Laptop Computer user, unknowingly, has to double-click or run the infected file before infection takes place. The most common way to get infected by a virus is to manually run a program that has the malicious code attached to it.
When you execute a program that's infected by a virus, the virus code will also run and try to infect other programs, either on the same PC Desktop Computer or on other PC Desktop Computers connected to it over a network.
Viruses are dangerous. The actual damage any particular virus can do depends on how the virus was programmed. Some viruses are deliberately designed to damage, corrupt, or even delete everything on your PC Desktop or Laptop Computer hard disk, some use an e-mail program to spread the themselves to other PC Desktop Computers while others may interfere with your normal computer's operation and use all memory available resources which eventually bring your desktop pc to a halt.