In the field of electrical engineering and electronics, ground supplies or ground can be defined as a reference point in any electrical circuit, this special reference point is referred as ground-GND and conveys a zero voltage. These voltage-measurements come under the umbrella of relative measurements. That is, a voltage estimation must be contrasted with another point in the circuit. If it isn't, the measurement is pointless.
Usually, this reference point is the foundation for all voltage-measurements inside the circuit. Be that as it may, not all voltage estimations are taken from this reference point. For example, if you are measuring the voltage over the above resistor in a resistive voltage-divider, your reference point would not be ground.
There can be numerous reasons for connecting the electrical circuits with ground (earth). Uncovered metal parts of appliances are connected to ground, so due to some internal faults, it will initiate defensive mechanisms such as circuit breakers or fuses in the circuit in order to eliminate power from the particular device.