Geosmin is a word that describes a smell that comes from the earth. It's a natural compound that's found in soil and in some bodies of water like rivers and lakes. Now, imagine you're playing outside on a sunny day, and after a rainstorm, you notice a smell that's like the earth or dirt. It's that specific smell that geosmin describes.
Geosmin is created by tiny living things called bacteria and algae. They are so small that you can't see them with your eyes! These tiny living things are all around us, in the soil, water, and air. When they start to grow and multiply, they release geosmin into the air, which is what you can smell.
Have you ever tried to grow plants or vegetables in your garden? If you have, then you might notice that your soil has a unique smell. That's because geosmin is created as the plants and bacteria decompose and break down.
Even though geosmin has a very strong and distinctive smell, it's not harmful to us. In fact, some people think that it smells nice and calming. It's also used in some perfumes and fragrances to give them a natural, earthy scent.