Mold in a household is a type of fungus that grows in damp, warm, and poorly ventilated areas, often appearing as black, green, or white patches. It thrives in places like bathrooms, basements, and kitchens, where moisture levels are high. Mold can cause health issues such as allergic reactions, respiratory problems, and irritation, particularly for sensitive individuals. It can also damage building materials, such as wood, drywall, and insulation. Preventing mold requires controlling moisture levels, ensuring proper ventilation, and addressing leaks or water damage promptly.