About Me 0014: Alt Attribute & SEO Optimization

SEO Optimization images is becoming increasingly more essential in SEO (Search Engine Optimization) for websites. The ALT attribute is a critical step that is sometimes forgotten. This can be a lost chance of better rankings.

In Google's webmaster guidelines, they advise using alternative text for the images on your site:

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

Why would they ask us to achieve that? The answer is simple, really; search engines have the same problem as blind users. They can't begin to see the images.

Many webmasters and inexperienced or unethical SEOs abuse the use of this attribute, trying to stuff it with keywords, looking to achieve a particular 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, trigger spam filters, which might create a penalty for your site's ranking. Even without such a penalty, your site's rankings won't take advantage of this tactic.
This process also puts persons who use screen readers at a greater disadvantage. Screen readers are software-based tools that really read aloud the contents of what is shown on the screen. In browsing the web, the alt features of images are read aloud as well.

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

An ALT attribute should not be used like a description or a label to have an image, though lots of people use it in that fashion. Although it may appear natural to assume that alternate text is a label or perhaps a description, it is not!

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

The goal is to provide the same functional information that the visual user would see. The alt attribute text should be the "stand in" when the look itself is unavailable. Ask yourself this: Should you replace the look using the text, would most users get the same basic information, and would it create the same response?
A few examples:

Some SEO Optimization Tips

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

If the image is meant to convey the literal contents of the look, then a description is appropriate.

If it is meant to convey data, then that information is what's appropriate.

If it's meant to convey using a function, then the function itself is what should be used.

Some Alt Attribute Guidelines:

Always add alt attributes to images. Alt is mandatory for accessibility and 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 do not bother users by uttering such things as "spacer image".

Keep in mind that it's the function of the image we are trying to convey. For example; any button images should not include the word "button" within the alt text. They ought to emphasize the action performed by the button.

Alt text should be based on context. The same image inside a different context may need drastically different alt text.

Attempt to flow alt text with the remainder from the text because that is how it will be read with adaptive technologies like screen readers. Someone listening to your page should hardly be aware that a graphic image can there be.
Please keep in mind that utilizing an alt attribute for each image is needed to meet the minimum WAI requirements, that are used as the benchmark for accessibility laws in UK and the remainder of Europe. Also, they are necessary to meet "Section 508" accessibility requirements in the US.

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

Eye-Candy
Mood-Setting
Content and Function

I. Eye-Candy

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

Never alt-ify eye-candy unless there's something there that will boost the usability from the site for somebody utilizing a non-visual user agent. Make use of a null alt attribute or background images in CSS for eye-candy.

II. Mood-Setting

This is 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 may not be considered essential, but they're essential in that they help frame what is going on.

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

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

Most times this will depend on context. Exactly the same image inside a different context may need drastically different alt text. Obviously, content ought to always be fully available. The way you go in 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 can also be so as.
The reason many authors can't understand why their alt text isn't working is they don't know why the images are there. You have to determined exactly what function a picture serves. Think about what it's about the image that's vital that you the page's intended audience.

Every graphic includes a reason behind standing on that page: since it either enhances the theme/ mood/ atmosphere or it is critical to what the page is attempting to describe. Understanding what the look is perfect for makes alt text simpler to write. And exercise writing them definitely helps.
A way to look into 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 create the page understandable to the listener?

Besides the alt attribute you have a couple more tools available for images.
First, in level of descriptiveness title is in between alt and longdesc. It adds useful information and may add flavor. The title attribute is optionally rendered by the user agent. Remember they are invisible and never shown like a "tooltip" when focus is received through the keyboard. (So much for device independence). So make use of the title attribute only for advisory information.
Second, the longdesc attribute points to the Link to a complete description of an image. When the information found in an image is important to the meaning of the page (i.e. some important content would be lost if the image was removed), an extended description than the "alt" attribute can reasonably display ought to be used. It can offer rich, expressive documentation of a 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 really a long description of the image...The aim is by using any length of description essential to impart the facts from the graphic.

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

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

Oftentimes, you're best just choosing your gut instinct -- if it's not necessary to include it, and when you don't possess a strong urge to get it done, don't include that longdesc.

However, if it's necessary for the whole page to operate, then you've to include the alt text (or title or longdesc).

What's necessary and what's not depends a lot on the function of your image and its context on the page.

The same image may require alt text (or title or longdesc) in a single spot, although not in another. If the image provides absolutely no content or functional information alt="" or background CSS images might be appropriate to make use of. But if the image provides content or adds functional information an alt would be required and perhaps a long description would be so as. In many cases this type of thing is a judgement call.