A mushroom is a type of fungus that typically has a cap, stem, and gills. They can be found in various environments, including forests, fields, and gardens. Mushrooms play a crucial role in ecosystems by breaking down organic matter and recycling nutrients back into the soil. There are thousands of mushroom species, some of which are edible, while others can be toxic. Common edible varieties include button mushrooms, shiitake, and portobello. Mushrooms are also used in cooking for their unique flavors and textures, making them a popular ingredient in many dishes worldwide.