The hot wire goes to a breaker-panel and then to electricity grid and finally to a transformer somewhere. While the neutral line is connected with a bar in the breaker-panel and goes directly to the electricity grid and then to the transformer. Mostly, these wires’ colors are respectively black, white.
To understand why having a ground in household appliances is important, the video explained a use-case; a microwave-oven with 3 wires electricity plug where the electricity flows between the hot and the neutral, while the ground is connected to the external case. However, if the hot wire isolation gets damaged and attached to the case, the grounded case will make a low resistance path for the electricity. This will protect you from an electric shock because the electricity in this low resistance path will be very high forcing the breaker switches off.
Having a ground in the electrical system can play a role in the places where lightning can occur by forming a discharging path for charged cases in your house.
To understand more about household ground and other different meanings and applications of earth and ground watch the complete video below:
Source: Adafruit Blog