Answer:
If the light bulb had never been invented, we would use natural sunlight as light during the day and fire or candles when we cannot see the sun. Since the light of candles is rather dim, most people would also sleep and wake up early, with the sun. The streets would be darker at night, even in urban areas.
Many other inventions that use the light bulb may not have been invented, or would be different. For example, our computer screens and television screens are forms of small light bulbs. Car headlights use light bulbs as well.
