A computer virus can come in many forms. They are commonly spread by email: what happens is that the virus scans the address book of the user on the affected machine, and sends messages to other users. When the message is opened by another user the process repeats. There is also a type of virus known as a Trojan horse, which poses as a legitimate piece of software. In many cases, a computer virus simply slows down the network the computer is on, particularly mail servers. Some, however, are more damaging: many an inadvertent virus download has ended with a user losing some or all of the data on his or her machine.
Because the average user has no way of knowing when a virus download has occurred, we use antivirus software, and regularly conduct virus scans. There are many, many types of antivirus software available, and there is both free and commercial software. One of the most popular free packages is called AVG, which will conduct virus scans and email scans using up to date virus definition files. The most popular commercial software is Symantec antivirus, which covers all aspects of virus prevention.
Virus scans are the most important part of virus prevention, and any antivirus software will have an update feature that will download the latest virus definitions files as new viruses become known. After obtaining antivirus software, the first thing to do is to update it with the most current virus definitions files, and then do a full scan of the machine. If any virus infected files are found, they can hopefully be removed with little trouble.
The machine should be rebooted after a virus scan, in order to prevent any virus on the machine from regenerating itself. One the computer has been rebooted, the most important element of virus protection to set up is a 'live scan' feature, whereby the antivirus application constantly scans the computer's files in the background and looks for and removes a virus if it finds one.
In recent years, the most common way for a virus to spread has been through email, and particularly with Microsoft outlook email software. Any good antivirus program will automatically scan any incoming and outgoing email for viruses, and remove them automatically.
Once antivirus software has been properly set up, the whole process should be fairly seamless for the average user: the software will automatically update and scan the machine in the background. The one thing to keep in mind is the affect on system performance, and users with older machines may find the Symantec software slows down their machines noticeably, and may choose to go with AVG instead.
Whatever piece of software the user chooses, once it is properly set up, the average user should have little to no problems detecting and removing a computer virus if it comes his or her way. With the antivirus software available today, most of the problems caused by computer viruses and their removal have become a thing of the past, so that the average user should have little to fear when it comes to viruses.