Viruses, worms, Trojan horses, phishing, and spyware are security threats to your computer.
You're probably familiar with some of these terms from the news media: viruses, worms, Trojan horses, phishing, and spyware. To take steps that make your computer more secure, you need some basic information about what the dangers are.
Most of the security threats mentioned involve a piece of malicious software (or code) that is intended to run on your computer without you knowing about it. It may be hidden inside another file or program, or run silently in the background. Most malicious software is designed to replicate itself and infect other files or computers. One way of doing this is by getting all your contacts' addresses and sending itself as an "infected" e-mail message that appears to come from you.
What exactly the malicious code does to your computer depends on what it is and how destructive it is. It may be designed to merely annoy, or it may actually harm your computer by deleting files or programs.
Here are a few definitions, so that you know what you're dealing with:
Virus Software (or code) written with the express intention of replicating itself. A virus attempts to spread from computer to computer by attaching itself to another file or program.
Worm Software that replicates independently by sending itself to other systems through network connections.
Trojan horse Software that appears to be useful or harmless but that contains hidden code designed to exploit or damage the system on which it is run.
Spyware Software that can display advertisements (such as pop-up ads), collect information about you, or change settings on your computer, generally without appropriately obtaining your consent. You usually download spyware without knowing it by visiting untrustworthy Web sites.
Phishing A way of extracting personal information from you such as bank or credit card details, normally done via e-mail. There are also some phishing schemes designed to put spyware on your computer. The good news is that Outlook 2007 has new anti-phishing features.