vaulted bedroom with light coming in the windows
The ability to adjust the light inside is part of what can make a home more or less comfortable.
Light is necessary for many activities: reading, growing plants.
Most common use of natural light comes from the sun. If a place has plenty of windows, the sun illuminates most of the house for the duration of the day. When it is night, the moon is a source of light, but not sufficient enough for many activities. Artificial lighting makes it possible for people to continue activities such as reading, studying (homework), sewing, and other crafts.
The most common source of light for an average household usually comes from light bulbs, when light from the sun is not enough to light a room sufficiently to do the desired tasks.