What does the f number mean on a lens and how does it affect the quality of the photographs taken?

The f-number on a lens represents the aperture size, which controls the amount of light entering the camera. A lower f-number (e.g. f/2.8) means a larger aperture and more light, resulting in a shallower depth of field and better low-light performance. A higher f-number (e.g. f/16) means a smaller aperture, less light, and a greater depth of field. The choice of f-number can impact the sharpness, clarity, and overall quality of the photographs taken.