Most digital cameras will take the picture at a size large enough for quality printing. However if you are sending this picture by email or posting them on the web, you will want to reduce the size of the image so they will transfer faster and are easier to view on the receiver's screen. Think what a surprise it would be for your client to receive a photo image so large it dominates the whole screen of his computer. You don't want to loose valuable customers because of length of time it takes to download the graphics.