Lenses are transparent objects made of glass or plastic which have the ability to refract light. In geometric optics, lenses are classified into two types: converging lenses and diverging lenses.

• Converging Lenses: These lenses are thicker in the middle and thinner at the edges. Converging lenses are also known as convex lenses. They have the ability to bring parallel rays of light together to a single point called the focal point. The distance between the lens and the focal point is known as the focal length.
• Diverging Lenses: These lenses are thinner in the middle and thicker at the edges. Diverging lenses are also known as concave lenses. Unlike converging lenses, they spread out the parallel rays of light and appear to diverge from a virtual focal point.