Computer Virus

1. What is a computer virus ?

Computer Viruses are executable computer programs. Like biological viruses, they find and attach themselves to a host. Just as a cold virus finds and attaches itself to a human host, a computer virus attaches itself to an item, such as a computer startup area (boot record) or an executable file.

Most viruses stay active in memory until you turn off your computer. When you turn off the computer you remove the virus from memory, but not from the file, files, or disk it has infected. So, the next time you use your computer the virus program is activated again and attaches itself to more programs. A computer virus, like a biological virus, lives to replicate. Some computer viruses damage the data on your disks by corrupting programs, deleting files, or even reformatting your entire hard disk. Most viruses, however, are not damaging; they simply replicate or display messages.

2. Viruses do the following :

Infect executable program files, such as word processing, spreadsheet, or operating system programs.

* Infect disks by attaching themselves to special programs in areas of your disks called boot records and master boot records. These are the programs your computer uses to start up.

* Infect a file before it is attached to an email message, data disks and disks used to transfer programs.

3. Viruses do not :

* Damage hardware, such as keyboards or monitors. Though you may experience strange behaviours such as screen distortion or characters not appearing when typed, a virus has merely affected the programs that control the display or keyboard. Not even your disks are physically damaged, just what's stored on them. Viruses can only infect files and corrupt data.

* Infect write-protected disks or  text-based email messages.