Guard hairs are the longer, coarser hairs found on the outer layer of an animal's fur. They serve as a protective barrier against environmental elements, such as water, dirt, and UV rays. These hairs help to keep the underfur dry and insulated, which is essential for maintaining body temperature. In many mammals, including dogs, cats, and deer, guard hairs play a crucial role in their overall appearance and health. The texture and color of guard hairs can vary widely among species, contributing to their camouflage and helping them blend into their surroundings for protection against predators.