Depth of field and Aperture

I have been exploring depth of field, which can be controlled using aperture priority, using a wide aperture gives a close up focus and tends to blur the background, emphasising the subject or object which is close to you as the photographer. Whereas a narrow aperture will give a much larger depth of field, giving focus to a wider range, showing the background more clearly. 

Wide aperture would be more appropriate for portraits and narrow aperture would be used for landscape photography.

Wide aperture:

 Narrow aperture: