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Electronics speak in two languages. A digital signal is simple on or off, while an analog one varies smoothly. Both matter in your projects.

A digital signal has only two states: HIGH or LOW, like a light switch. There is nothing in between, just yes or no.

An analog signal can be any value across a range, like a dimmer slowly fading a lamp from off to full brightness.

Temperature, light, and sound never jump between two values. They flow smoothly, so the real world is mostly analog by nature.

On an Arduino, an analog reading is really a voltage between 0V and 5V. A higher voltage simply means a higher value.

A push button is the perfect digital input. It is either pressed or not, so you read it as HIGH or LOW with digitalRead.

A turning potentiometer sends a smoothly changing voltage. Turn it slowly and the value glides, so you read it as analog.

The Uno keeps them separate. Digital pins are labeled D0 to D13, while the analog input pins are labeled A0 to A5.

You match the function to the signal: digitalRead for on or off pins, and analogRead for the smooth analog inputs.

Your chip cannot truly feel a smooth voltage. An ADC converts that analog voltage into a number the code can use.

Choosing the right type avoids bugs. Read a sensor with analogRead and a switch with digitalRead, and your data stays correct.

Which input belongs to the analog world?

You learned that digital is on or off while analog is a smooth range. Buttons are digital, knobs are analog. Match the read function to each.