If you're creating Web pages, always include alternative text that can appear in place of images. Alternative text appears in the following circumstances:
When a Web page is displayed in a browser with images turned off (to increase speed)
When a Web page is displayed in a browser customized for an individual with a visual disability (the alternative text can be read aloud by the computer, whereas an image cannot)
When an image cannot be accessed from the Web server
In Internet Explorer, as a ScreenTip that can be used to explain an image
To create alternative text, right-click on an image, choose Format Picture from the shortcut menu, and click the Web tab. The Web tab of the Format Picture dialog box appears (see Figure 13.31).
In the Web tab's Alternative Text box, enter the descriptive text. Though the dialog box is large, it's usually best to keep the text as concise as possible. If the alternative text is associated with a navigation button or another graphical element, make sure that readers know what clicking the button will do. When you're finished, click OK.