What is a computer virus

Virus
Trojan
spyware
Zombies

Virus

A malicious program that copies itself from computer to computer, then does some damage like deleting users files. It could be worse and send your credit card details too bad people who might clean out your account.

Trojan

A malicious program that is disguised inside another program, e.g. inside a “Browser Toolbar “

Spyware

Spyware is a term for hidden software that spies on your computer activities and may report to somewhere else in the world. One example sends data from computers all over the world to an address in China. Sometimes this data contains credit card numbers you used or are stored on your computer, other times it might contain details of web sites you visited, which might be interesting for marketing companies.

Zombie

A ‘zombie’ is a PC that has been taken over by a hidden program which uses its internet connections to send out malicious or spam emails (Or ‘Denial of Service’ attacks, where millions of internet messages are sent to maliciously swamp some target web site, often for political or criminal reasons)