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Let’s look at the six factors you should keep in mind as you create Web images.
People who print images on paper don’t have to worry about what their readers will use to look at the images. You do. The Web is accessed every day by millions of Macs, Windows-based PCs, phones, tablets, and other kinds of devices. The graphics you use in your Web page should be in a format that each of these operating systems can recognize. Presently, the three most widely used formats on the Web are GIF, PNG, and JPEG. Current browsers can view all three image formats.
You want to choose a format that gives you the best quality with the smallest file size.
The JPEG format is good for color photographs because it handles large amounts of color and it compresses well, so your file sizes will be small . It is a lossy format, so you lose some of the image’s original information when you save it as a JPEG, but usually this is a worthy compromise, because your pages load quickly. We’ll talk more about this in the “Speed” section.