Depth of field is the distance in a photograph between the nearest and farthest objects in a scene that appear particularly sharp in an image. You can have a narrow depth of field or a larger depth of field depending on the type of photograph you want. A narrow depth of field is when only a small part of the image is in focus this could mean having a certain object being focused and the background blurred. On the other hand you could have a large depth of field where the whole image is in focus and looks very sharp. Depth of field is controlled by the camera’s aperture.
For example an aperture of f/2.8 would give a large depth of field whereas an aperture of f/22 would give a narrow depth of field.