Not in focus( focused before sensor), so image is blur   

 Focus-It means the mechanism by which user adjusts the camera lens to get an optimum viewpoint of a scene. It helps to get a clear and sharp image of the specific point of the scene. 

                               Not in focus( focused behind the sensor), so image is blur


                                              focused on sensor properly, hence a clear image on screen


 There are two types of focus system, auto-focus and manual focus. In auto-focus the lenses are automatically adjusted by a motor drive. And in manual focus, user have to rotate the focus ring to adjust the lenses for focus.

Generally, a smartphone uses Auto focus system for focusing purpose.

 Auto focus (AF) contrast-detection auto-focus phase-detection auto-focus (PDAF), laser auto-focus