We're very much used to electric streetlights these days, but keeping the streets bright at night used to be powered by candles or gas.
Lamplighters had to light lamps (as the name would suggest!) but also extinguish them in the morning. Dependent on where in the world the lamplighter lived, he could have a leisurely stroll around the town lighting lamps, or he could be charging around frantically trying to ensure they were all lit in time. For example, there were tens of thousands of lamps in London, England alone, but in contrast, there were under 1,000 in Lowell, Massachusetts, in the US.
The job was considered to be prestigious, and was often passed down from father to son, though sometimes, the duty was performed by women, too. It was a relatively safe job, but one risk was being blown off their ladders by a gas buildup in the light chamber.
Lamplighters also made money on the side by capturing rare bugs attracted to the light in the lamps and selling them to insect collectors.
As you can imagine, when electricity and light bulbs became commonplace, the career of a lamplighter was snuffed out. (Source: HowStuffWorks)