The camera lens collects so many of the light rays which are bouncing about and redirects them to a single point using glass, resulting in a crisp image.
Since most of these light beams collide on a digital camera sensor or a piece of film, a crisp image is formed.
A camera lens is an optical lens or collection of lenses used in conjunction with a camera body and mechanism to capture pictures of things on photographic film or other media capable of preserving an image chemically or electronically.
Hence, the camera's lens creates an inverted and decreased image.