What is mold? Molds are fungi that grow and thrive in moist, dark, and warm environments. Neither plant nor animal, fungi are their own special thing, with a kingdom dedicated to these unique organisms. Along with tasty mushrooms, fungi are responsible for the creations of yeast and penicillin. At least 100,000 species of fungi have been discovered, with many more yet to be found. Mold spores are everywhere, and any substance that contains carbon atoms will support mold growth — even the oil from your skin that's left when you touch surfaces.
What causes mold? Mold thrives in the presence of lots of moisture, so bathrooms and kitchens are the first spots you may find moldy areas in your home. But a small roof leak or a dripping toilet can introduce moisture to your home, inviting mold to grow in areas that you might not be able to see. Even your carpet is susceptible to mold growth. For mold to grow, there needs to be mold spores in the area; a food source for the mold to grow, such as wood, drywall, or fabric; and a dark, warm, and moist environment with air flow. Humidity, leaking pipes, and even condensation from your toilet tank can breed mold.