What's aperture and how does it affect the outcome of a photograph?

Aperture refers to the opening in a camera lens that controls the amount of light entering the camera. It affects the outcome of a photograph by influencing the depth of field, which determines how much of the image is in focus. A wider aperture (smaller f-stop number) creates a shallower depth of field, blurring the background and emphasizing the subject. Conversely, a narrower aperture (larger f-stop number) increases the depth of field, keeping more of the image in focus.