Sharpening takes many forms. If your camera uses standard picture controls, that you have not modified, some level of sharpening is already applied and this is called capture sharpening. The various picture controls have different Capture sharpening values. Many of us set this to zero upon opening our images by using revised Picture controls where sharpening has been taken to zero and then we add an edit step that applies what we believe is a good starting point for capture sharpening. final sharpening is dependent upon the final purpose of the image as a post to the web will have a different sharpening level than a print, a print usually being sharpened more, or as you have pointed out when you resize an image.