Monoterpenes are tiny molecules that are often found in plants, like a little secret ingredient that helps them smell nice. They are made up of only ten carbon atoms and 16 hydrogen atoms, and their structure is like a small, simple balloon.
Just like a balloon, monoterpene molecules can pop open and release their scent. They can do this when a plant is disturbed, like when you brush past a lavender bush and smell the sweet fragrance.
Some common monoterpene molecules include limonene, which is found in citrus fruits and is often used in cleaning products, and pinene, which smells like a forest and is found in pine trees.
Scientists have found that these tiny molecules can have some helpful properties, like being antimicrobial, meaning they can kill germs, and also being anti-inflammatory, meaning they can help reduce swelling in the body.
So, just like how we use spicy herbs to add flavor to food, plants use monoterpene molecules to add a pleasant scent and sometimes even a little extra "oomph" to keep themselves healthy.