A lens is a curved piece of glass or clear plastic that bends light to make things look bigger, smaller, clearer, or closer than they really are. Your eye contains a natural lens that focuses light so you can see. Eyeglasses and contact lenses help people whose eyes need assistance focusing properly. Cameras use lenses to capture sharp images, and microscopes use powerful lenses to reveal tiny organisms invisible to the naked eye.

The word can also mean a way of looking at or understanding something. When you view a problem through the lens of friendship, you think about how it affects relationships. A historian might examine an event through the lens of economics, focusing on money and trade rather than battles and kings. Your personal experiences create a unique lens through which you see the world. Someone who grew up by the ocean might view water differently than someone who grew up in the desert.

The shape of a lens matters tremendously: convex lenses (thicker in the middle) make things look bigger, while concave lenses (thinner in the middle) make things look smaller. This simple curved shape changed human history, making possible telescopes that revealed distant planets, microscopes that discovered bacteria, and cameras that captured memories.