Sams Teach Yourself HTML 4 in 24 Hours

By Dick Oliver

• Table of Contents
  • Copyright
  • About the Author
  • Acknowledgments
  • Tell Us What You Think!
  • Put Your HTML Page Online Today
  • I. Your First Web Page
  • Hour 1. Understanding HTML and XML
  • Hour 2. Create a Web Page Right Now
  • Hour 3. Linking to Other Web Pages
  • Hour 4. Publishing Your HTML Pages
  • II. Web Page Text
  • Hour 5. Text Alignment and Lists
  • Hour 6. Text Formatting and Font Control
  • Hour 7. Email Links and Links Within a Page
  • Hour 8. Creating HTML Forms
  • III. Web Page Graphics
  • Hour 9. Creating Your Own Web Page Graphics
  • Hour 10. Putting Graphics on a Web Page
    • Placing an Image on a Web Page
    • Labeling an Image
    • Images That Are Links
    • Horizontal Image Alignment
    • Vertical Image Alignment
    • Summary
    • Q&A
    • Workshop
  • Hour 11. Custom Backgrounds and Colors
  • Hour 12. Creating Animated Graphics
  • IV. Web Page Design
  • Hour 13. Page Design and Layout
  • Hour 14. Graphical Links and Imagemaps
  • Hour 15. Advanced Layout with Tables
  • Hour 16. Using Style Sheets
  • V. Dynamic Web Pages
  • Hour 17. Embedding Multimedia in Web Pages
  • Hour 18. Interactive Pages with Applets and ActiveX
  • Hour 19. Web Page Scripting for Non-Programmers
  • Hour 20. Setting Pages in Motion with Dynamic HTML
  • VI. Building a Web Site
  • Hour 21. Multipage Layout with Frames
  • Hour 22. Organizing and Managing a Web Site
  • Hour 23. Helping People Find Your Web Pages
  • Hour 24. Planning for the Future of HTML
  • VII. Appendixes
  • A. Readers' Most Frequently Asked Questions
  • B. HTML Learning Resources on the Internet
  • C. Complete HTML 4 Quick Reference
  • D. HTML Character Entities

Labeling an Image

Each <img /> tag in Figure 10.1 includes a short text message, such as alt="Friendly Fen". The alt stands for alternate text because this message will appear in place of the image in older Web browsers that don't display graphics, or for those users who choose to turn off automatic image downloading in their Web browser preferences.

People who are using the latest Web browser software will see the message you put in the alt attribute, too. Because graphics files sometimes take a while to transfer over the Internet, most Web browsers show the text on a page first with the alt messages in place of the graphics (as shown in Figure 10.3).

Figure 10.3 People will see the alt messages while they wait for the graphics to appear.

Even after the graphics replace the alt messages, the alt message appears in a little box whenever the mouse pointer passes over an image. In Figure 10.2, for example, the mouse arrow is over the photo of Han Zol, and the alt message Honest Han is showing. The alt message also helps anyone who is visually impaired (or is using a voice-based telephone interface to read the Web page).

You should generally include a suitable alt attribute in every <img /> tag on your Web pages, keeping in mind the variety of situations where people might see that message. A very brief description of the image is usually best, but Web page authors sometimes put short advertising messages or subtle humor in their alt messages. For small or unimportant images, it's fine to omit the alt message altogether.

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