One of the best features of the iPhone camera is Portrait mode. By simulating an expensive DSLR camera and lens setup, images captured in Portrait mode blur the background, highlighting the subject and providing a more professional result. Those shooting in Portrait mode may not even realize this setting has more to offer when editing photos.
The background blur, or bokeh, is not fixed as it would be when capturing images using different aperture (or f-stop) settings. In fact, on the iPhone, the background blurriness can be adjusted after the picture is taken.