Viruses
Computer virus
n.
A computer program that is designed to replicate itself by copying itself into the other programs stored in a computer. It may be benign or have a negative effect, such as causing a program to operate incorrectly or corrupting a computer's memory.
-The American Heritage ® Dictionary of the English Language, Fourth Edition
So here’s the scene: You’re browsing the net, in your own little world, merrily downloading anything that catches your eye, visiting web pages on a whim, and suddenly there’s a flash of metaphorical lightning and the screen goes blank, or something akin to that sort of virtual disaster. Chances are your system, while you’ve been happily surfing the internet superhighway, has acquired some sort of virus.
Admittedly, most computer failures are due to something other than a virus, but the danger is there. Viruses can be hidden in all sorts of things; music downloaded from the net, the new ‘computer game’ attached to an e-mail, all sorts of things. Some viruses even install themselves automatically when the website that they reside on is visited. And these viruses can do all sorts of horrible things to your computer. Such as prevent you form using it, uninstall your operating system and even delete every file on your computer.
But it’s not the end of the world; there are protection systems in place, and following simple security rules will keep you and your data safe.
-Alex
Always use a firewall/anti-virus protection. These pieces of software will protect your computer from most harmful viruses, especially the most up to date versions.
Avoid visiting web pages they you either don’t trust or have been warned about, as they may contain viruses.
The same care should be taken to avoid downloading files or programs from sources that you don’t trust, especially .exe files.
Never ever open up an attachment on an email from someone who you don’t know; this is absolutely vital to your security.
Don’t open attachments even from people you know, unless they specifically mention the attachment, the attachment may have been added without the knowledge of the sender, while it was being sent.
-Microsoft virus security page