Image "Alt Tags" are very important. They are intended to be used by text only browsers, to show text to describe what the image is about. The "Alt" stands for ALTernate.
These days, most people use website browsers which do show images. Internet Explorer also shows the alt text as a yellow box, with text, when you mouse-over an image.
Some disabled people use text-only browsers to view web pages, or web page readers, which use the alt tag to explain the image. Because of this it is good practice to use alt tags to explain the images you use.
Another advantage of using alt tags, is that search engines use "robots" to look at your website. These computer programs cannot make sense of the images you have used (They see the site very much like a text-only browser). They can guess with the help of the surrounding text, the image name, and the text in the alt tag. For this reason, using alt tags, can get your page a higher website ranking!
For more help with Alt Tags and promoting your website, please contact us for a free consultation.