Differences between program mode and immediate mode

Program mode (the "P" on the mode dial of most DSLRs) means that the camera still sets the exposure for you. It chooses the correct aperture and shutter speed for the light available, so your shot is correctly exposed. Program mode also unlocks other functions that give you more creative control over your images... Immediate mode in computer graphics is a major pattern of API(Application Programming Interface) design in graphics libraries, in which the client calls directly cause rendering of graphics objects to the display, or in which the data .