surfaces:

A converging lens is a curved lens that bends light rays inward to meet at a single point called the focal point. This is the lens shape you find in magnifying glasses—thicker in the middle and thinner at the edges. When you hold a magnifying glass over a newspaper, the words appear larger because the converging lens brings light together to form a real, magnified image.

A diverging lens does the opposite. It's thinner in the middle and thicker at the edges, spreading light rays outward as if they came from a point behind the lens. You see this in peepholes on doors throughout Nigerian homes—they let you see a wider view of visitors outside while making everything appear smaller and farther away.

Both lens types follow the same basic rule: light bends when it passes through them, and where it bends determines what image you see.