The HTML tags describing an image that appears when the mouse is rolled over the image on a Web page. Helpful for people who view pages in text-only mode. Some search engines look for keywords in ALT tags.

If you use images in your Web pages, its good practice to include Alt text for every image that a visitor to your site will see. ALT tags filled with keywords can also be used to boost your keyword frequency and help you achieve better rankings.

ALT tags also make your site more accessible to visually impaired people using text readers. Even if your Website is content rich, the alt tags allow you to reinforce what is highly important, the key terms, within the content.

The overall impact of using ALT tags, in terms of search engine optimization, is low. As they have become abused by webmasters who fill alt tags with streams of keywords, the major search engines have lowered the importance of ALT tags in their algorithms. However, ALT tags are a required element for standards-based HTML coding. Every image must have an ALT tag, and each ALT tag must be properly implemented.

It's great news for SEO though, because as long as you don't "stuff" your images full of keywords, it's a great way to add targeted keywords to your pages content.

Spiders eat alt tags up because while they can't "read" an image, they sure can read an alt tag.

A great example of an alt tag is if there was a picture of a brown dog with spots, you would have alt tags for it that said "brown dog with spots".

ALT tags serve the following functions in seo and web design.

* Make sites accessible to the visually disabled.

*Describe images so that search engines and the disabled can see them.

*Allow keywords to be added to your pages with out cluttering them up.

*They should be used for every image on your site, within reason.