Computer Virus

from the site of: http://en.wikipedia.org/wiki/Computer_virus#Boot_Sector_Virus

What is Computer Virus all about?

A computer virus is a self-replicating computer program written to alter the way a computer operates, without the permission or knowledge of the user. Though the term is commonly used to refer to a range of malware, a true virus must replicate itself, and must execute itself. The later criteria is often met by a virus which replaces existing executable files with a virus-infected copy. While viruses can be intentionally destructive—destroying data, for example—some viruses are benign or merely annoying.

Effects of Computer Viruses

Some viruses are programmed to damage the computer by damaging programs, deleting files, or reformatting the hard disk. Others are not designed to do any damage, but simply to replicate themselves and make their presence known by presenting text, video, and audio messages. Even these benign viruses can create problems for the computer user. They typically take up computer memory used by legitimate programs. As a result, they often cause erratic behavior and can result in system crashes. In addition, many viruses are bug-ridden, and these bugs may lead to system crashes and data loss.

Use of the word "virus"

The word virus is often claimed to be the acronym of Vital Information Resources Under Siege, although this is obviously a backronym. The word is derived from and used in the same sense as the biological equivalent. The term "virus" is often used in common parlance to describe all kinds of malware (malicious software), including those that are more properly classified as worms or Trojans. Most popular anti-virus software packages defend against all of these types of attack. In some technical communities, the term "virus" is also extended to include the authors of malware, in an insulting sense.

The English plural of "virus" is "viruses". Some people use "virii" or "viri" as a plural, although computer professionals seldom use these words. For a discussion about whether "viri" and "virii" are correct alternatives of "viruses", see plural of virus.