Here's a question you've probably never asked: how do computers compute things?
Some people might answer by explaining that computers follow a very long list of very simple instructions that humans give them, but that response sparks more questions than it answers.
For one thing, how can the computer understand our instructions? We've all seen how flipping a light switch can turn a light on, but people communicate with words, not switches! Also, even if we accept that computers can parse what we tell them to do, we aren't any closer to knowing how they actually do it.
To really understand what makes computers work, we need to open one up and zoom in a few hundred-thousand times to get a good look at a piece of silicon that's only a handful of nanometers in size. It's called a transistor.
There are billions of these things inside a single modern computer, and it's been estimated that over 10 sextillion (that's 10,000,000,000,000,000,000,000) of them have been made since they were invented less than 100 years ago. So, what makes transistors so important? How can something so small process information?
This is a diagram of what the inside of a transistor ? might look like. The square yellow regions have a small negative electric charge and the large, rectangular blue region has a small positive electric charge. ?
Negative charge occurs when there are extra electrons and positive charge occurs when there aren't enough, so let's add some electrons and empty spaces where electrons want to go to our diagram.