Define depth of field.

Depth of field refers to the range of distance in a photograph that appears sharp and in focus. This concept is crucial in photography because it affects how much of the scene in front of and behind the subject is kept in focus. A shallow depth of field results in a small area in focus with a blurred background and foreground, which is often used in portrait photography to emphasize the subject. In contrast, a deep depth of field keeps most elements in a scene sharp, which is important in landscapes and architectural photography where clarity throughout the image is desired. Understanding depth of field helps photographers control the composition and focus points in their images more effectively.