The Depth of Field is controlled by the focus and aperture of a camera and is the distance between the nearest and furthest image in the frame. For instance, if a shot is using a shallow focus, the background will be more blurred out, making it easier to have a specific character stand out to the audience.

Whereas a deep focus will have everything in the frame in focus, with nothing necessarily standing out more than anything else. For instance, The Revanant (Alejandro González Iñárritu, 2016) used a a lot of deep focus shots throughout so as to keep everything of equal importance in the frame.