1 photographs and complex images using the JPEG
Most suitable for continuous-tone images such as photographs.
It can contain up to 16 million kinds of representation, images of different colors. This is a "lossy" format, because some of the information will be lost when the image reduce file size,
Does not support transparency, the document is relatively small, so web pages more efficient display. JPEG does not support animation.
2 monochrome image, logo and geometry use PNG or GIF
PNG image is a monochrome image and the most suitable configuration of the line, (e.g., logo, clipart, and small image). PNG image may represent may contain millions of different colors, PNG has three,: PNG-8, PNG-24, and PNG-32 depends on how much you need to represent colors, PNG will compress the file to the compressed file size but do not lose information, so this is a "lossless" format, PNG allows the color to "transparent" so that the image can be displayed the following things. Compared with the corresponding JPEG files, PNG files larger, but the number of colors being used. May be smaller than the corresponding GIF file, it may be even greater.
Like PNG, GIF image most suitable for monochrome images and lines formed (such as logo, clip art images and small text). GIF images can represent up to 256 different colors, GIF is a "lossless" format, GIF also supports transparency, but allows only one color is set to "transparent" GIF files are often larger than the corresponding JPEG files, support for animation .