A fungus is a living thing that isn't a plant or an animal, but belongs to its own group of life. Mushrooms are the most familiar fungi (the plural of fungus), but the mushroom you see is just the fruiting body. The main part of the fungus lives underground or inside dead wood, spreading through tiny threads that break down and absorb nutrients.

Unlike plants, fungi can't make their own food from sunlight. Instead, they get energy by decomposing dead things or living on other organisms. When you see mold growing on old bread or fuzzy spots on forgotten fruit, you're watching fungi at work. Some fungi help forests thrive by connecting tree roots underground and sharing nutrients. Others cause problems: athlete's foot is a fungal infection, and certain fungi can destroy crops.

Fungi play a crucial role in nature as recyclers. Without them, dead leaves, fallen trees, and animal remains would pile up instead of breaking down into rich soil. Scientists have discovered that fungi are more closely related to animals than to plants, which surprised many people. Some fungi are delicious to eat, like button mushrooms or truffles, but many are poisonous, so wild mushrooms should only be eaten when an expert confirms they're safe.