What does the term "lens mm" refer to in photography and how does it impact the quality of the image captured?

The term "lens mm" in Photography refers to the focal length of a camera lens, measured in millimeters. A higher focal length (e.g. 50mm, 100mm) means a narrower field of view and more magnification, while a lower focal length (e.g. 18mm, 24mm) means a wider field of view. The focal length impacts the perspective, depth of field, and compression of the image, which in turn affects the quality and composition of the photo.