Resolution refers to the sharpness and clarity of an image, measured by the number of pixels per inch (PPI) in a bitmap image. Higher resolutions allow for more image detail and larger print sizes. Common resolutions include 256x256 for low-quality cameras, up to 4064x2704 for 4 megapixel cameras and over 12 million pixels for high-end cameras. The optimum resolution depends on whether the image will be displayed on screen or in print, with 72 PPI standard for screen and 300 PPI for print.