What are viruses? Where do they come from?

What are Viruses and Where Do They Come From?
One of our readers once asked in an email whether spraying Lysol on her computer would help protect it from viruses.

It was an example of how confusing viruses can be.

Normally, viruses are associated with germs and are biological, not mechanical or electrical.

So what is a computer virus and why is it called that?

Computers are machines that do only what you tell them to do. The way you tell them what to do is by creating a list of instructions. That's what a computer program is. A long and very complex list of instructions that has been written by a computer programmer. That's why computers are so versatile. Toasters toast bread and that's all. Alarm clocks tell time and wake you up and that's about it. Flashlights illuminate the darkness. There seems to be no limit as to what a computer can do, however, and that's because it sits there like a willing servant awaiting its instructions. If you give it a program that tells it how to design an airplane wing, that's what it will do. If you give it instructions on how to keep track of your grocery list, that's what it will do. If you want to create a personalized greeting card, just load a program for that into your computer and go for it. Computers can even do all of those things at once because they can be reading several different lists of instructions at the same time..

It all depends on the the program that has been written and loaded into the machine.

But what if there is a computer programmer who is a practical joker or, worse, wants to cause harm? All that person has to do is create a program, a list of instructions, telling the computer how to do it. What if the programmer wants that program to hit as many computers as possible? He just includes that in the instructions. For example, he may tell the program to hide itself in a file and if that file gets copied or sent to another computer, to have the program set itself up on the new computer, hide itself in some new files that may be copied or sent to other computers, and so on. Or he may even instruct the program to use email to send itself to as many other computers as possible. That kind of a program is acting very much like a germ. It is an unwelcome intruder that can cause harm and has been passed from one host to another through some kind of contact. An "infected" computer or file can "infect" another and an outbreak of infections can occur.