The Program That Copies Itself

The story

A computer cannot think for itself. That is the first thing to know about it. It is a machine that follows instructions, one after another, millions of times faster than a person could, but it follows them blindly. A list of instructions is called a program. And that means a computer is only ever as good, or as bad, as the instructions somebody gives it.

Now imagine a program written to be sneaky. Its instructions say, roughly, this. Hide inside another program. When that program runs, wake up and quietly copy me somewhere new. A program that spreads by copying itself is called a computer virus, and it earned that name honestly, because that is just how a real virus behaves in your body, borrowing your own cells to make copies of itself, then moving on.

One of the first viruses ever to escape into the world was not built by a criminal at all. More than forty years ago, a fifteen-year-old schoolboy in America wrote one as a prank. It rode from computer to computer on floppy disks, the little plastic squares people used to carry files about before the internet reached most homes, and every fiftieth time an infected machine started up, a teasing little poem appeared on the screen. His friends were not amused. But the world had been given a warning wrapped inside a joke. If a bored teenager could do this, anyone could.

Today, sneaky programs are usually after something. Some spy. Some steal passwords. Some lock up a computer's files and demand money to set them free. A few slip in on their own, through tiny holes in old software. But most arrive dressed as something friendly, a free game, a link in a message, an attachment marked urgent. The trick is hardly ever clever machinery. The trick is fooling the human at the keyboard into opening the door themselves.

Which is wonderful news, in a way, because it means the strongest shield is not an expensive gadget. It is you, being just a little bit suspicious. Never tap surprise links, even ones that seem to come from a friend, because a friend's account can be stolen and puppeted. Download games only from the official stores, never from strange websites promising free treats. Let your devices install their updates, because an update is a repair crew, sealing up the little holes that sneaky programs crawl through. And if a message ever tries to frighten you or hurry you, saying act now, you have won a prize, your account will vanish, do the opposite. Slow down and show a grown-up. Hurry is the fraudster's favourite tool, and calm is its enemy.

A computer obeys whoever gives it instructions. Guard whose instructions it hears, and that obedient, blindingly fast machine stays exactly what it was always meant to be, which is truly and completely yours.