The main source of light is the Sun.

Explanation:
The Sun is the main source of light in our solar system. It emits light and heat through a process called nuclear fusion. The Sun is a giant ball of gas, primarily hydrogen and helium, which produces energy through the fusion of hydrogen atoms to form helium. This process releases an enormous amount of energy in the form of light and heat.

Importance of Sun as a source of light:
The Sun plays a crucial role in providing light and heat to the Earth. Its light allows us to see and helps in various activities such as reading, working, and carrying out daily tasks. The light from the Sun also enables photosynthesis, a process by which plants convert light energy into chemical energy to produce food.

Other sources of light:
While the Sun is the main source of light, there are also other sources of light that we use in our daily lives. These include:

1. Window pane: A window pane does not produce light itself but allows light from outside to enter a room. It acts as a medium for the transmission of sunlight, which is the main source of light.

2. Torch: A torch is a portable handheld device that produces light through the use of batteries and bulbs. When the switch is turned on, the electrical energy from the batteries is converted into light energy by the bulb, providing a source of light in dark areas.

3. Candle: A candle produces light through the process of combustion. When the wick of a candle is lit, the heat melts the wax, which is then drawn up the wick and vaporized. This vaporized wax reacts with oxygen in the air, producing a flame that emits light.

While these sources of light are useful in certain situations, they are not the main source of light like the Sun. The Sun's light is essential for our existence and provides the majority of the light we rely on for everyday activities.