A computer virus is a program that is designed to damage your computer, programs, and files. Like a virus in a living thing, a computer virus can spread if it is not removed. Some viruses are more dangerous than others. One of the most common places for a computer virus to appear is on a file found on the Internet or attached to an E-mail. For example, you may have a virus that just pops a message box on your screen, and then the virus is disabled, or you can have a virus that deletes half of your hard drive.
             Computer viruses didn't really exist until the mid 1980s. The first computer viruses were created in university labs to demonstrate how much of a threat the vicious code could be.
             There are many kind of viruses that exist today. Some of the most common of Computer Viruses are: File Viruses, Boot Sector/Partition Viruses, Multi-Partite Viruses, Trojan Horses, File Overwriters, Polymorphic viruses, and Stealth Viruses.
             A File Virus is the most common kind of virus. These kinds of viruses usually infect .EXE and .COM files, which are the main component of a program or application. A file virus can insert its own code into part of the file, so that when the infected program file is run, the virus is executed first.
             Most file viruses are memory resident. Because of this, they can easily attach themselves to other programs that are being run and start to infect that file. A simple virus will overwrite and destroy a host file, immediately letting the user know that there is a problem because the software will not run. Because these viruses are immediately sensed by the computer, they have a less chance to spread. More complex written viruses will cause more damage, spread easier, and are harder to be detected.
             Boot sector viruses infect hard drives and floppy disks by putting itself on the boot sector of the disk, which has the code that is run at boot up. Booting up from an infected floppy, allow...