As mentioned earlier (repeatedly), web pages are nothing more than text
and references to files and directions where to place those files (images)
into a web page. In the "early" days of web pages, graphic images were
a luxury and it was often desirable to see a web page with nothing more than
the text and a reference as to what picture would be seen, should that be
desired. With slow modem connections to the Internet, it was often wise
to turn off images and get the information needed in text form. To allow for
this, web browsers had the ability to choose whether or not to load images.
If a browser came to a page with images but had been told to turn images off,
it would display some text in place of the image. This text is known
as Alternate Image Tags or "Alt Tags."
There are other uses for Alternate Image Tags. When you load a page that is graphically intense (many and/or large numbers of graphics), you may have noticed that sometimes words appear before the images appear. These are the Alternate Image Tags and they often appear while the graphics are loading.
Also, if a web page is accessed by a visually impaired person, they may have the web page "read" to them by the computer. If that is done, images will be "referenced" verbally by the Alternate Image Tags. With some browsers, pointing to an image gives you a "balloon" that describes the picture using the Alt Tag for that image.
To add Alternate Image Tags to a web page, you can add the text when you add the image or after you have the image in place. If the image is already placed in your web page, click on the picture and pull down FORMAT>Image Properties (or you may double-click the image). Then in the Location Tab box, click the alternate text button and enter the information and press OK