Computer viruses are a very legitimate concern for microcomputers. Viruses are most often contracted from accessing a floppy disk containing the virus. With a few exceptions, viruses are transmitted as part of a program file. One recent exception that is becoming a problem is transmission of Microsoft Word or Excel macro viruses. These can be transmitted via document files.
Many programs are available to guard against and to remove viruses from floppy and hard disks.
In order to be effective, the programs need to be updated regularly to guard against new strains of virus. A recent concern about viruses is not a virus but rather hoaxes about viruses. Probably hundreds of thousands or even millions of email messages have been sent around the Internet warning users about viruses that don't exist. Usually the warning is about opening an email message which will do serious damage to the users computer. There is no known way that a virus could be part of an email message.