What are ALT tags and why should I use them?
ALT tags are tags attached to images on web pages to describe them to site visitors with text browsers or visual impairments. When optimizing a site, webmasters try to include relevant keywords in ALT tags. Simply stuffing your ALT tags with multiple keywords is considered spam and is not recommended. We do, however, recommend writing descriptive text in your ALT tags that includes keywords. First, however, make sure that you adequately describe the images to those using text readers or text browsers.
How do I use ALT tags?
Use an ALT tag to describe every single image on your site. If you use text in an image, you can use the same text in the tag. Try to include important keywords in your ALT text. That way, when a search engine spiders your site, it may give you a higher ranking for those keywords. At the very least, use ALT tags for the top images on your page, since the top of the page is particularly significant to search engines. Here’s an example of an ALT tag:
<img src=”image.gif” alt=”Descriptive text with keywords”>
ALT tag text should be in the form of a sentence rather than a list. There are all sorts of situations in which users see them — and not just the ones who use textonly browser settings. Readers see ALT text when they mouse over images and while images are loading.
The limits of ALT tags
ALT tags are an excellent way to deal with images, but they’re not the solution. Search engines still prefer text to ALT tags and images. That’s why we recommend creating an alternative textual navigation for your web site. If you have a site that uses graphics heavily, consider creating an all-text version. Also, if you have a graphic with a link, always provide a description of the link below. You will gain a broader audience and make your site easier for search engines’ spiders to index.
Avoiding spam
Search engines are very well aware of webmasters who place repetitive, irrelevant keywords in their ALT text. ALT text should be optimized, but like text on your site, it should be created for users first, with search engine considerations being secondary.