A convex lens is best described as:

A convex lens is characterized by being thicker in the middle than at the edges. This design allows it to converge light rays that pass through it. When parallel light rays enter a convex lens, they are bent inward and focused to a point on the opposite side, known as the focal point. The curvature of the lens increases the ability to focus light, making it useful in applications like magnifying glasses, glasses for farsightedness, and cameras.

This property distinguishes a convex lens from other types of lenses, such as concave lenses, which are thinner in the middle and diverge light rays. Understanding the specific structure of a convex lens helps explain its optical behavior and the role it plays in various optical devices.