Introduction to Viruses
Defining the Value of Information Security
When you start a program that's infected by a virus, the virus code will execute (run) and try and infect other programs. This can infect the same computer or other computers connected to it on a network. The newly infected programs will try to infect more programs and computers.
When you share a copy of an infected file with other computer users, opening the file may also infect their computers; and files from those computers may spread the infection to yet more computers.
If your computer is infected with a boot sector virus, the virus tries to write copies of itself to the system areas of floppy disks and hard disks. Then the infected floppy disks may infect other computers that boot from them, then the virus on the computer will try to infect more floppies inserted into it.
