A purifier is a device designed to remove impurities from air, water, or other substances. In air purification, it typically uses filters or other technologies to capture dust, allergens, and pollutants, improving indoor air quality. Water purifiers, on the other hand, use methods like filtration, reverse osmosis, or UV light to eliminate contaminants, making water safe for drinking. Purifiers are commonly used in homes, offices, and industrial settings. They can help reduce health risks associated with poor air or water quality. Popular types include HEPA filters for air and activated carbon filters for water purification.