Rods are elongated, cylindrical objects that can be made from various materials such as metal, wood, or plastic. They are commonly used in construction, sports, and various mechanical applications. For example, a fishing rod is designed to help anglers catch fish, while a metal rod might be used to reinforce concrete structures. In biology, rods refer to a type of photoreceptor cell found in the retina of the eye. These cells are responsible for vision in low-light conditions and help detect movement. Unlike cones, which are responsible for color vision, rods are more sensitive to light and play a crucial role in night vision.