.GIF (pronounced ‘jiph’) - Graphics Interchange Format The GIF format uses 8-bit color and efficiently compresses solid areas of color while preserving sharp details like those in line art, logos, or type. You also use the GIF format to create an animated image and preserve transparency in an image. GIF is supported by most browsers. The GIF format uses LZW compression, which is a lossless compression method. However, because GIF files are limited to 256 colors, optimizing an original 24-bit image as an 8-bit GIF can subtract colors from an image. GIF image with Selective color, and GIF image with Web color You can choose the number of colors in a GIF image and select options to control how colors dither in a browser. GIF supports background transparency or background matting, in which you blend the edges of the image with a Web page background color.
	.JPG (‘jay-peg’) - Joint Photographic Experts Group The JPEG format supports 24-bit color, so it preserves the broad range and subtle variations in brightness and hue found in photographs and other continuous-toned images. A progressive JPEG file displays a low-resolution version of the image in the Web browser while the full image is downloading. JPEG is supported by most browsers. JPEG format compresses file size by selectively discarding data. Because it discards data, JPEG compression is referred to as lossy. A higher quality setting results in less data being discarded, but the JPEG compression method may still degrade sharp detail in an image, particularly in images containing type or vector art. Note: Artifacts, such as wave-like patterns or blocky areas of banding, are created each time you save an image in JPEG format. Therefore, you should always save JPEG files from the original image, not from a previously saved JPEG. Original image, and optimized JPEG with Low quality setting The JPEG format does not support animation or transparency. When you save an image as a JPEG file, transparent pixels are filled with the Matte color specified in the Save For Web dialog box. To simulate the effect of background transparency, you can match the Matte color to the Web page background color. If your image contains transparency and you do not know the Web page background color, or if the background is a pattern, you should use a format that supports transparency (GIF, PNG-8, or PNG-24).
	.PNG (pronounced ‘peeng’) - Portable Network Graphics The PNG-8 format uses 8-bit color. Like the GIF format, PNG-8 efficiently compresses areas of solid color while preserving sharp detail like those in line art, logos, or type. Because PNG-8 is not supported by all browsers, you may want to avoid this format when your image must be accessible to a wide audience. For more information on browser support for PNG, see your browser's documentation. The PNG-8 format uses a more advanced compression schemes than GIF, so a PNG-8 file can be 10% to 30% smaller than a GIF file of the same image, depending on the image's color patterns. Although PNG-8 compression is lossless, optimizing an original 24-bit image as an 8-bit PNG file can subtract colors from the image. Note: With certain images, especially those with simple patterns and few colors, GIF compression can create a smaller file than PNG-8 compression. View optimized images in GIF and PNG-8 format to compare file size. As with the GIF format, you can choose the number of colors in an image and select options to control how colors dither in a browser. The PNG-8 format supports background transparency and background matting, in which you blend the edges of the image with a Web page background color.
	.TIFF (pronounced ‘tiph’) - Tagged Image File Format Tagged-Image File Format (TIFF) is used to exchange files between applications and computer platforms. TIFF is a flexible bitmap image format supported by most paint, image-editing, and page-layout applications. Also, virtually all desktop scanners can produce TIFF images. TIFF is THE undisputed graphics industry standard file format for images. It is uncompressed and therefore contains all orignial information from the saved file. This also means that it is also the largest in file size.

Image File Formats