Aperture refers to the opening in a camera lens that controls the amount of light entering the camera. It is measured in f-stops, with a lower f-stop number indicating a larger opening, allowing more light to reach the sensor. This affects exposure and depth of field, influencing how sharp or blurred the background appears in a photograph. In photography, a wider aperture (like f/2.8) creates a shallow depth of field, isolating the subject from the background. Conversely, a smaller aperture (like f/16) increases depth of field, keeping more of the scene in focus. Understanding aperture is essential for achieving desired artistic effects in images.