Why wire switches together?

The last chapter introduced the transistor, the tiny switch inside a computer. Logic begins when those switches are connected.

Inside a computer, those switches are transistors. To make the connections easy to follow, our drawings use simple switches and a lightbulb. The bulb shows the arrangement's answer: on means yes, off means no.

Use a microwave as a simplified example. Suppose it runs only when the door is closed and the start button is pressed. If either switch leaves a gap in the electrical path, the oven stays off.

A connected path like this is called a circuit.

Two switches can be placed one after the other on one path, or side by side on separate paths. The switches are identical. The arrangement changes the answer.