Depth of field is the zone where a photo is focused on. So, where the photo appears sharper and clearer. Every picture has a point of focus where the camera’s lens is focused. But behind and Infront of that is an area that appears sharp as well.  The is deep depth of field and shallow depth of field. Deep depth of field is usually a large zone where everything appears sharp. From the front to the back. Photographers use this a lot when shooting a landscape. Shallow depth of field creates a blur around the main subject. The main subject becomes sharp blurring out the background for better attention.