Odor facts for kids

An odor (or odour) is a tiny bit of a chemical compound that floats in the air. Humans and animals can smell these tiny bits using their sense of olfaction, which is just a fancy word for smelling.
Smells can be called many things. We often use the word smells for both nice and not-so-nice odors. Words like fragrance, scent, or aroma usually mean a pleasant smell. You might hear these words used for perfumes or in the food industry. On the other hand, words like stench, reek, and stink are only used for really bad smells.
What Are Smells?
A smell is a feeling caused by tiny molecules floating in the air. Most smells come from organic compounds. But some inorganic substances, like hydrogen sulfide (which smells like rotten eggs) and ammonia (a strong cleaning smell), also have odors.
Smelling something happens in two steps. First, your nose senses the smell. Special parts inside your nose, called receptors, pick up the tiny smell molecules. Second, your brain processes this information. The part of your brain in charge of smelling figures out what the smell is.
Because of how we smell, it's really hard to measure odors in a scientific way. How someone feels about a smell is very personal. Things like your gender, age, how healthy you are, and even your mood can change how you react to a smell. Also, people often notice common smells less, like their own body odor, compared to new or unusual smells.
For most people, smelling something doesn't tell them exactly what a substance is made of. It mostly tells them if they like the smell or not. However, people who work with smells a lot, like flavorists (who create food flavors) and perfumers (who create perfumes), can often identify many different chemicals in a complex mix just by smelling them.
Smells for Talking: Pheromones
Pheromones are special odors that animals use to communicate with each other on purpose. They are like secret messages sent through the air!
For example, a female moth can release a pheromone that attracts a male moth from many kilometers away. Honeybee queens also constantly release pheromones. These smells help control what the rest of the hive does. Worker bees can release pheromones too. They might use them to call other bees to a new home when a swarm moves. Or they might release an "alarm" smell if the hive is in danger.
In mammals, some pheromones are picked up by a special part of the nose called the vomeronasal organ. Other pheromones are sensed by regular odor receptors in the nose, just like other smells.
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In Spanish: Olor para niños