2. What is a computer virus

In the search box on the right, type the term computer virus and see what you can find out for yourself

A Computer Virus is a computer program that is designed to copy itself repeatedly and attach itself to other computer programs.

In the early days of personal computing (1980's) some of the people who created them had a certain misplaced sense of humour. For example, there was a virus that caused all the characters on screen to drop into a heap at the bottom of the display. Very annoying, but relatively harmless.

However, quite soon some really nasty versions came out that were deliberately designed to corrupt and delete your files as well as trying to copy itself everywhere.

Viruses can cause an immense amount of time wasting and financial loss for people and businesses.

For example, the "Melissa" virus was so effective in spreading itself that many huge corporations had to shut down their email systems until the virus could be contained.

To give you a flavour of the nuisance they cause, here is a virus alert bulletin from an email scanning company when the "Mydoom" virus was spreading by email attachments.

From Message Labs, 17 Jan, 2004, http://www.messagelabs.com

* Processing between 50,000 and 60,000 new copies per hour, "W32/Mydoom.A has exceeded the infamous SoBig.F virus in terms of copies intercepted, and the number continues to rise."
* Message Labs collected over 1.2 Million copies of W32/Mydoom.A-mm
* At its peak infection rate, about 1 in 12 emails on the Internet were MyDoom Viruses

.It is estimated that there are now around 53,000 computer viruses in existence