Computer Viruses

Computer viruses bear more than a passing resemblance to their biological namesakes: they usually reproduce by inserting their code into legitimate programs, much as biological viruses insert their genetic material into a host cell, causing it to be reproduced. They spread quickly between today's highly connected computers, which run similar operating systems and programs, much as colds and flu thrive in dense populations of genetically similar humans.

There are other, more subtle similarities. As in nature, computer viruses spread most rapidly before they are detected and defences ban be mobilised against them. The most widespread viruses are rarely those that incapacitate a computer quickly, as 'killing' the host stops a virus from continuing to multiply and spread.

Within this biological analogy, anti-virus software plays a similar role to an organism's immune system and up-to-date virus signatures are similar to vaccinations. Just as vaccinating the majority of the population against a virus such as polio prevents an epidemic, computers gain 'herd immunity' from a threat if a suitable majority have anti-virus software that can stop it.