Lenses are transparent optical devices that bend light to form images. They are typically made from glass or plastic and come in various shapes, such as convex (curved outward) and concave (curved inward). Convex lenses converge light rays to a focal point, making them useful in devices like magnifying glasses and cameras. In contrast, concave lenses diverge light rays, which is helpful in applications like eyeglasses for nearsightedness. Lenses are essential components in many optical instruments, including microscopes and telescopes. They help magnify objects or focus light to enhance visibility. The science of how lenses work is based on the principles of refraction, which describes how light changes direction when passing through different materials.