Sustainable Competitive Advantage: Alt Attribute & SEO Optimization

SEO Optimization images is becoming more and more important in SEO (Search Engine Optimization) for websites. The ALT attribute is a critical step that is sometimes forgotten. This is often a lost opportunity for better rankings.

In Google's webmaster guidelines, they advise the use of alternative text for that images on your web site:

Images:. Use the alt attribute to provide descriptive text. In addition, we recommend utilizing a human-readable caption and descriptive text around the image.

Why would they ask us to do that? The answer is easy, really; search engines have a similar problem as blind users. They cannot see the images.

Many webmasters and inexperienced or unethical SEOs abuse the use of this attribute, attempting to stuff it with keywords, looking to achieve a certain keyword density, which isn't as relevant for rankings now since it was previously.

On the other hand, high keyword density can, on some search engines like google, trigger spam filters, which might result in a penalty for your site's ranking. Even without such a penalty, your site's rankings will not benefit from this plan.
This process also puts persons who use screen readers in a greater disadvantage. Screen readers are software-based tools that actually read aloud the items in what's shown on the screen. In browsing the net, the alt features of images are read aloud as well.

Imagine hearing a paragraph of text which is followed by repetitions of many keywords. The page would be far from accessible, and, to put it bluntly, would be found quite annoying.
What exactly is an Alt attribute?

An ALT attribute should not be used as a description or perhaps a label for an image, though many people use it in that fashion. Although it might seem natural to assume that alternate text is really a label or a description, it is not!

The words used inside an image's alt attribute ought to be its text equivalent and convey the same information or serve exactly the same purpose that the image would.

The thing is to supply the same functional information that a visual user would see. The alt attribute text should be the "stand in" when the look is not available. Think about this: If you were to replace the look with the text, would most users get the same basic information, and would it generate the same response?
Some examples:

Some SEO Optimization Tips

If your search button is a magnifying glass or binoculars its alt text should be 'search' or 'find' not 'magnifying glass' or 'binoculars'.

If the image is supposed to convey the literal items in the image, then a description is suitable.

If it is designed to convey data, then that data is what is appropriate.

If it is designed to convey the use of a function, then your function itself is what ought to be used.

Some Alt Attribute Guidelines:

Always add alt attributes to images. Alt is mandatory for accessibility as well as for valid XHTML.

For images that play merely a decorative role in the page, use an empty alt (i.e. alt="") or a CSS background image to ensure that reading browsers don't bother users by uttering things like "spacer image".

Remember that it is the function from the image we're attempting to convey. For instance; any button images shouldn't range from the word "button" within the alt text. They ought to emphasize the action performed through the button.

Alt text should be determined by context. The same image in a different context may require drastically different alt text.

Attempt to flow alt text with the rest of the text because that's the way it will be read with adaptive technologies like screen readers. Someone hearing your page should hardly be aware that a graphic image is there.
Please remember that utilizing an alt attribute for each image is needed to meet the minimum WAI requirements, which are used as the benchmark for accessibility laws in UK and also the rest of Europe. They are also required to meet "Section 508" accessibility requirements in america.

It is useful to categorize non-text content into three levels:

Eye-Candy
Mood-Setting
Content and Function

I. Eye-Candy

Eye-Candy are stuff that serve no purpose apart from to make a site visually appealing/attractive and (in many cases) fulfill the marketing departments. There is no content value (though there might be value to some sighted user).

Never alt-ify eye-candy unless there is something there that will enhance the usability from the site for someone using a non-visual user agent. Use a null alt attribute or background images in CSS for eye-candy.

II. Mood-Setting

This is actually the middle layer of graphics which may serve to set the mood or set happens as it were. These graphics aren't direct content and could 't be considered essential, but they are important in they help frame what is going on.

Attempt to alt-ify the 2nd group as makes sense and it is relevant. There may be instances when doing so might be annoying or detrimental to other users. Then avoid it.

For example; Alt text that is identical to adjacent text is unnecessary, and an irritant to screen reader users. I suggest alt="" or background CSS images in such instances. But sometimes, it's important to get this content inside for those users.

Usually this will depend on context. The same image inside a different context may require drastically different alt text. Obviously, content should always be fully available. How you use this case is really a judgment call.

III. Content and Function

This is when the image is the actual content. Always alt-ify content and functional images. Title and long description attributes may also be so as.
The reason many authors can't figure out why their alt text isn't working is they don't know why the images exist. You need to determined exactly what function an image serves. Think about what it's about the image that's important to the page's intended audience.

Every graphic has a reason behind standing on that page: since it either enhances the theme/ mood/ atmosphere or it is critical to what the page is trying to explain. Understanding what the look is perfect for makes alt text easier to write. And practice writing them definitely helps.
A method to check the usefulness of alternative text is to imagine reading the page over the telephone to someone. What would you say when encountering a particular image to make the page understandable towards the listener?

Aside from the alt attribute you have a couple more tools at your disposal for images.
First, in degree of descriptiveness title is within between alt and longdesc. It adds useful information and may add flavor. The title attribute is optionally rendered by the user agent. Remember they're invisible and never shown as a "tooltip" when focus is received via the keyboard. (A lot for device independence). So make use of the title attribute only for advisory information.
Second, the longdesc attribute points towards the URL of a complete description of an image. When the information contained in an image is essential towards the concept of the page (i.e. some important content would be lost if the image was removed), a longer description than the "alt" attribute can reasonably display should be used. It may provide for rich, expressive documentation of the visual image.

It ought to be used when alt and title are insufficient to embody the visual qualities of an image. As Clark [1] states, "A longdesc is a long description of an image...The goal is by using any length of description necessary to impart the details from the graphic.

It would not be remiss to hope that a long description conjures a picture - the look - in the mind's eye, an analogy that is true even for that totally blind."

Even though alt attribute is mandatory for web accessibility and for valid (X)HTML, not every images need alternative text, long descriptions, or titles.

In many cases, you're better off just going with your gut instinct -- if it's not essential to include it, and if you don't have a strong urge to get it done, don't add that longdesc.

However, if it's essential for the entire page to work, then you have to include the alt text (or title or longdesc).

What's necessary and what's not depends a great deal on the function of your image and it is context on the page.

Exactly the same image may require alt text (or title or longdesc) in one spot, although not in another. If an image provides simply no content or functional information alt="" or background CSS images might be appropriate to use. However, if the image provides content or adds functional information an alt will be required and perhaps a long description would be in order. In many cases this type of thing is really a judgement call.