Explaining Computer Viruses (with zombie chefs)

Ever wondered how to explain the concept of computer viruses? My PC recently acquired a virus. While I was killing it (using my anti-virus software), one of my children observed, “Oh! Computers get sick, too?”  Cute? Well, adults often have the same question. So here’s an answer and explanation using analogies and a fun story involving zombies…

No, computers can’t get biological diseases. Like most personal computing concepts, the term is metaphorical, borrowed from the real-world equivalent. A real human or animal virus is an entity that intrudes — gets into the inside of the body — and goes about doing something it shouldn’t, usually causing harm.

The same is true in computing. In The Ultimate PC Primer, I explain that computer programs (software) are really sets of instructions, like a recipe. The computer is just a mindless machine following these instructions. In fact, it knows nothing else except how to follow its instructions — precisely. And ideally, that’s what you want from a computer: consistency and precision in obeying the instructions given it. That’s what makes it useful for you. It follows instructions presumably intended to produce a helpful result. But what would happen if some instructions were given to it that were designed to do something harmful?

Imagine you are entering a cooking or baking competition. You must organize and direct the efforts of five chefs who will prepare five dishes you have selected from five recipes. The completed dishes will be presented to the judges of the competition. The chefs will follow any instructions exactly. (They’re like mindless chef-zombies who know only about following recipes.) All you need to do is provide the instructions for how they are to prepare each dish. So you select five sophisticated recipes from your recipe collection or cookbook and set them out for the zombie chefs to follow. But…

Now imagine that someone else — a competitor  — sneaks into the kitchen and modifies the recipes. This mischievous individual inserts other instructions in several of the recipes — instructions intended to make the dish turn out horribly. Perhaps this villain even tampers with the settings on your oven. If these sinister actions went undetected, the instructions on the recipes would not produce the anticipated result. In fact, in addition to losing the competition, harm might even be done to your kitchen.

In the same way, a computer virus is a set of misleading instructions — intentionally and carefully crafted bad directions intended to cause harm or make your computer fail to follow its ordinary instructions. (If you’re wondering who would want to do such a thing, you also need to wonder who would want to rob a bank or hijack an airliner. There are troublemakers in the world, in all disciplines, and computing is no exception.) In computer terms, this is generically called malware. Viruses, “trojan horses” (or “trojans” for short), and “worms” are all specific types of little computer programs with malicious instructions. Computer viruses may also attempt to replicate and spread their instructions to other computers, “infecting” the other PCs if possible. Hence the analogy drawn from real-world viruses which also replicate and spread to infect other hosts.

How do computer viruses travel? Like human viruses, they need a host — a computer — to live inside of. So to spread, the two computers must connect somehow. A virus can hitch a ride on a portable removable disk (a topic I cover in Lesson 9 in The Ultimate PC Primer), being carried like salmonella on finger food at a buffet. Or, they can be transferred by direct contact: when computers exchange information using the Internet (discussed in Lesson 14).

If you’re wondering, “Golly! This all sounds scary, risky, and dangerous! Isn’t there a way to inoculate or at least treat my PC?”  Yes, operating a PC does have some risks these days because nefarious-minded programmers continue to make viruses and other malware.  That’s why there are specific “anti-virus” programs you can buy to keep your PC protected. It’s a bit like a doctor giving an immunization and also standing by with an arsenal of antibiotics, in case anything slips in that requires treatment. To return to the kitchen analogy, it’s like hiring a guard and bouncer to keep your recipes safe.

Now, for all the explanation of viruses and malware I’ve just done, if you carefully skim the Table of Contents in The Ultimate PC Primer you’ll note that this topic is suspiciously absent. It begs the question: If viruses and other malware are out there in abundance, why isn’t security and anti-virus prominently featured in a book allegedly covering the ultimate basics in PC concepts? Answer: it’s generally not necessary for the audience of the book, because in this day and age, most PC novices will never encounter viruses. Pre-installed (or easily acquired) security software mostly protects personal computers from such threats today. Unless a user knows enough to engage in risky business and intentionally bypass security software, such threats will likely never be an issue. Besides, the book is a primer designed to encourage newcomers to computing. Security measures and viruses sound scary, and one of my prime goals was to take the fear out of learning to embrace personal computers. Provided that adequate security software is installed on the PC, most ordinary users will never need to fear viruses and malware. With my virus, I ran the anti-virus scan and it removed the problem without issue or further intervention.

So, for the same reasons, make sure you and your computer are immunized: to keep the bad stuff out. And then go bake something. Just watch out for the zombie chefs.*


* Author’s note: in The Ultimate PC Primer, I actually use the term “robot chef” when explaining software using the cooking/recipe analogy. In general, I think “robots” aid the story-based explanation better. It’s just that zombies are so terribly trendy right now. As such, I decided to change it up for this blog post. Please, no comments about zombie chefs cooking brain-based dishes.


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