For example, in broad daylight, your camera probably took the picture at 1/250 of a second with aperture 16 (the two elements that make a proper exposure, shutter speed and aperture). Indoor, your camera probably took the picture at 1/60 of a second with aperture 5.6. The smaller the aperture (higher number) will give your picture a greater depth-of-field. The larger aperture (smaller number) will give you less depth-of-field. You may make your indoor background looks sharper if your digital camera lets you change the aperture setting (like aperture priority). Just set the aperture smaller (higher number). The camera will adjust the shutter speed to slower. In this case, you may need a tripod or brace yourself to steady the camera. Also your subject has to be still for longer. Hope this helps.