Currently, the two most popular formats used for images are the JPEG and GIF compression formats. Since uncompressed images can have such huge file sizes and therefore be slow to load, a web designer uses the compression format that gives the best looking image at the smallest file size. The general rule of thumb is flat images(drawings) with large horizontal regions of the same color, use GIF. The file type,JPEG, gives the best compression if you are working with detailed multicolored pictures(photographs). Note: Although the format is officially called JPEG, the file extension you use is .jpg, example: picturename.jpg. It is sometimes a good idea to save an image both ways to compare file size and image quality.

Please take a moment to read the following link. Read the first page you come to and 2 of the links at the bottom of the page. The links to read are called JPEG Examples and GIF Examples. Here is the link.

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