Water repellent refers to materials or coatings that resist the penetration of water. These substances create a barrier that prevents water from soaking into surfaces, making them ideal for outdoor gear, clothing, and building materials. Common examples include water repellent sprays and fabric treatments that enhance the durability and longevity of items exposed to moisture. The effectiveness of water repellent products is often measured by their ability to repel water droplets, which can be tested using the hydrophobic effect. This property is useful in various applications, including sportswear, footwear, and outdoor equipment, ensuring that users stay dry and comfortable in wet conditions.