Using the Internet can be very dangerous. There are many individuals who are constantly attempting to infiltrate the computers of unsuspecting Internet users to steal money or personal information. There are many different commercial antivirus software packages available to prevent these attacks, and they are widely used. A huge number of the computers that are brought to me have some kind of antivirus software installed on them by the user.
The popular perception is that once an antivirus software is installed on a computer, the user can freely browse the internet and download any file at all, and the antivirus software will protect them. This could not be further from the truth.
Installing antivirus software on your computer is similar to wearing a bulletproof vest every day. The bulletproof vest will protect you against some types of attacks, but not all. Similarly, antivirus software is constantly being updated to protect against the newest virus attacks, and will never detect every kind of virus. There are simply too many different types of viruses being created every day for antivirus software programmers to keep up with.
It is true that a bulletproof vest does offer some protection against physical attacks. However, if a person enjoys wandering down dark alleys in a major city late at night, it will only be a matter of time before something bad happens to them, even with a bulletproof vest. The same principle applies to avoiding virus attacks. The only near-guaranteed way to stay virus-free is to avoid shady websites and downloads.