Optical lenses are transparent pieces of glass or plastic that bend light to focus or disperse it. They are commonly used in devices like glasses, cameras, and microscopes. The shape of a lens determines how it interacts with light, allowing it to magnify images or correct vision. There are two main types of optical lenses: convex and concave. Convex lenses are thicker in the center and can converge light rays, making them useful for magnifying objects. Concave lenses are thinner in the center and diverge light rays, which helps in correcting nearsightedness in eyeglasses.