A voltmeter measures the electric potential difference (voltage) between two points in a circuit.

Analog voltmeters have a coil that moves a pointer based on the current caused by the voltage
Digital voltmeters use an analog-to-digital converter (ADC) to display the voltage as a number on the screen
It contains very high resistance, allowing only a tiny current to pass through
It is always connected in parallel so it can measure the voltage across two points without disturbing the circuit’s current.