Malware is an abbreviation of "malicious software" and covers any program or file that is harmful to a computer. This includes all computer viruses, worms, Trojan horses and spyware.

Spyware is a specific type of malware that monitors how a computer is used and sends reports to another computer via the internet, for example, logging credit card numbers or username and password entries to steal a person’s identity. Another example is rogue dialler software that causes a user’s PC to call a premium rate phone line instead of their ISP’s standard number.

Most security software and firewalls includes some sort of protection against known threats. However, in order to avoid these kinds of attack, you need to ensure that anything you download – whether from a Web site or in an email – is from a safe, secure, credible source.

See also: Guide to beating spyware