A light switch works because it has two stable positions. You can push it down and the lamp stays off, or push it up and the lamp stays on, even if your hand is gone.
Computers face the same core problem, but at much higher speed and smaller scale. A computer has to store a value in hardware and send that value across wires, even though real signals wiggle because of heat, electrical interference, and imperfect components. Using just two clearly separated states makes that job easier because the hardware only has to decide between two buckets, not many.
You can picture one bit traveling on a wire as a low voltage or a high voltage. When the wire is low, the computer treats it as 0, and when the wire is high, the computer treats it as 1. A bit is that choice between two stable physical states used to represent information.
Once you have 0 and 1, you can use them to answer a yes or no question. For example, 0 can mean NO and 1 can mean YES.
If you put multiple bits side by side, you get more distinct patterns. Two bits can describe four different cases, which is enough for something like directions. You might map 00 to North, 01 to East, 10 to South, and 11 to West.
Explore the possible patterns for 1, 2, and 3 bits.
Generate custom courses on any topic — with hands-on practice, AI guidance, and visuals built in.
Already have an account?
Those patterns only help if the hardware can read them reliably. On a real wire, the measured voltage is not perfectly steady, so the reader circuit has to compare the voltage against a boundary called a threshold and then decide whether it counts as low or high.
Now imagine trying to use four voltage levels instead of two, like level 0, 1, 2, and 3. The allowed range for each level gets narrower, so the same amount of noise is more likely to push a measurement across the wrong boundary and flip the interpreted value. With only two levels, you can leave a bigger safety margin between low and high, and that margin reduces read errors.
See how two voltage bands compare to four voltage bands under noise.