What appears to be in focus when the variable range goes from foreground to background?

Depth of field refers to the range of distance within a photo that appears acceptably sharp. When a photograph is taken, the depth of field determines how much of the scene from the foreground to the background remains in focus. A shallow depth of field will result in just a small part of the image being sharp, often keeping the subject in focus while blurring the background. Conversely, a deep depth of field allows both the foreground and the background to be in clearer focus, which is often desirable in landscape photography where the entire scene should appear sharp.

This discussion contrasts with exposure, which pertains to the amount of light that reaches the camera sensor and affects how bright or dark an image appears. Contrast involves the differences in luminance or color that make objects distinguishable, impacting the visual impact of an image, but not directly related to what is in focus. Sharpness is a measure of the clarity of detail in an image but is influenced by several factors, including depth of field. While related, it does not encompass the wider concept of what range appears in focus from foreground to background, which is captured by the term depth of field.