I thought I would throw some information I have learned thru long and hard experience as a Security Administrator for a large company. Note information here Viruses In computer security technology, a virus is a self-replicating program that spreads by inserting copies of itself into other executable code or documents. Thus, a computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells. Extending the analogy, the insertion of the virus into a program is termed infection, and the infected file (or executable code that is not part of a file) is called a host. Now that you have heard a technical definition, I will explain what this means. A virus simply is a small program that when executed, follows its own programming to replicate itself over and over in some fashion. There are many different types of viruses exist. I will really only describe two. The Worm and the Resident Virus since those tend to be the most prevalent in the wild of the Internet. The Worm The worm is a virus that is network aware. This means when a worm infects a computer it then engrains itself in the Operating System and then starts looking for other computers on a network to infect. Most worms actually dont cause many problems on the actualy computer, but they create nightmares for the actual Network that the computer sits on. This computer, starts sending THOUSANDS of requests from the infected computer looking for other computers to infect. This causes the network to become completely bogged down. Imagine a network of thousands of computers on it, all infected. This would basicaly take and any network and for the most part, cease it from functioning. The Resident Virus This virus usually is not network aware like the worm. When the resident virus infects a file, it integrates itself in the file waiting to be run. When then you run the file, in the background, the virus simply executes its payload. It infect other files and then runs in the background without your knowledge. It can then infect every file you run, thus spreading itself thru your actions. How do I protect myself from viruses? First, you MUST have an antivirus program. There are MANY out there you can purchase and there are a number that you can download for free. I would reccommend one of the following: AntiVirus Software you can Purchase ETrust EZ Antivirus Symantec's Norton Antivirus TrendMicro Antivirus Kapersky Anti-Virus Mcafee Antivirus AntiVirus Software you can Download for Free Grisoft Free Antivirus Clam Antivirus No matter what, download and install an Antivirus product. Protect yourself and protect others by having one. Second, make sure you consistantly update your antivirus programs definitions Definitions are additions to your program that help identify existing viruses and possibly help block ones that have yet to be identified. Most programs can be setup to downoad its updates automatically. But I reccommend running it by hand at least once a week to make sure you know its getting updated. Third, do not open any email in which you do not know who its from. Simply delete it. Most viruse epidemics are started by people who are unaware and simply open programs, attachments to emails and emails they know nothing about. On your home computer, question everything everyone sends you. Fourth, if you suspect you do have a virus I would suggest do the folowing. 1) Update your AntiVirus software immediately. 2) Scan your complete computer with your AntiVirus program you have installed. 3) Then go to Trend Micro's HouseCall website and have their free online scanner scan your pc as well. This will then help your figure out if you have been infected.