The two main graphics formats that Web browsers can read are GIF and JPEG. Each is suitable for different types of images, so it's important to know which one to choose.

GIF vs.JPEG

GIF is a graphic format using a compression designed by CompuServe. They have the extension '.GIF ' and are best used for illustration, line art and simple graphics that have little or no shading. They support up to 256 colors and use a lossless compression which allows for all detail to be maintained during the compression process.Most clip-art and text-based images on the Web are of the GIF format.

JPEG is a graphic format designed by Joint Photographic Experts Group (JPEG).  They have the extension '.JPG' and are best used for photographic images.  JPEG files can support up to 16 million colors as compared to GIF's 256 colors. It uses a lossy compression which means certain parts of images are permanently thrown away so that the files take up less storage space. Most photographic images on the Web are of the JPEG format.

Limiting Image Size

Making smaller images. Consider using only icons or similar type graphics on your page.  If you must use large graphics, use clickable thumbnails to link to the larger version.

Compress your images by choosing the right format for your graphics.  A good rule of thumb is to use GIF for illustration and line art images and use JPEG for photographic images.

Reducing colors in your images.  The fewer colors you include in your image, the less information the image needs to keep track of, as a result, the smaller the image size becomes.  For example, anti-aliasing, a technique that uses intermediate colors to blend edges in images, will increase your image size by 30% or more.