Depth of field refers to the range of distance within a photo that appears sharp and in focus. It is influenced by several factors, including the aperture setting of the camera, the distance from the subject, and the focal length of the lens. A shallow depth of field results in a blurred background, emphasizing the subject, while a deep depth of field keeps more of the scene in focus. Photographers often manipulate depth of field to create artistic effects or to guide the viewer's attention. For instance, using a wide aperture (like f/2.8) can isolate a subject, while a narrow aperture (like f/16) is useful for landscape photography, where clarity throughout the image is desired.