Lenses, one of the key optical elements used in geometric optics, can either converge or diverge light rays. A converging lens, such as a convex lens, brings parallel light rays together at a single point called the focal point. Conversely, a diverging lens, like a concave lens, spreads out incoming parallel rays. These properties of lenses are utilized in various optical devices and systems, such as cameras, eyeglasses, and microscopes.