Honeybees are very gentle, but sometimes can become nervous or aggressive when a beekeepers inspects the beehive- especially if the beekeeper accidently bumps the hive and the bees think they are in danger! The earliest beekeepers realized that if they were going to get the honey, they would have to distract the honeybees. So they invented the smoker.
So how does a smoker work? Well, when the honeybees smell something burning, they get busy eating honey for energy. If the building you were in was on fire, you would run out as fast as you can. Honeybees have to eat to have the energy needed to be able to fly. The smoker distracts them; they are busy eating honey and not worried about the beekeepers. The smoker also helps to cover up honeybee alarm pheromones. Pheromones are a type of chemical signal or scent; the alarm pheromone is produced when something is intruding on the hive- kind of like saying "watch out, there's somebody here!". When a beekeeper uses a smoker, it helps to cover up that scent!
Smokers do not hurt the bees in any way- it just helps to calm them down. During this time, beekeepers can inspect the hive to make sure that the honeybees are healthy and making honey!
"Bee in the Know": Beekeepers inspect their hives about every two weeks in the summertime.