About Me 0119: 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 often overlooked. This can be a lost opportunity for better rankings.

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

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

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

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

On the contrary, 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 this type of penalty, your site's rankings won't benefit from this plan.
This process also puts persons who use screen readers in a greater disadvantage. Screen readers are software-based tools that really read aloud the contents of what's 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 that is followed by repetitions of many keywords. The page will be far from accessible, and, to put it bluntly, will be found quite annoying.
What exactly is an Alt attribute?

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

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

The goal would be to supply the same functional information that the visual user would see. The alt attribute text should function as a "stand in" when the look is unavailable. Think about this question: If you were to replace the image using the text, would most users get the same basic information, and wouldn't it create the same response?
Some examples:

Some SEO Optimization Tips

If a search button is really a magnifying glass or binoculars its alt text ought to be 'search' or 'find' not 'magnifying glass' or 'binoculars'.

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

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

If it's meant to convey the use of 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 so that reading browsers do not bother users by uttering things like "spacer image".

Keep in mind that it is the function from the image we are attempting to convey. For example; any button images should not range from the word "button" in the alt text. They should emphasize the action performed through the button.

Alt text ought to be based on context. Exactly the same image in a different context may require drastically different alt text.

Try to flow alt text with the rest of the text because that's how it will be read with adaptive technologies like screen readers. Someone listening to your page should hardly remember that a graphic image is there.
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 rest of Europe. They are also necessary 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 other than to create a site visually appealing/attractive and (in many cases) satisfy the marketing departments. There isn't any content value (though there may be value to some sighted user).

Never alt-ify eye-candy unless there's something there which will boost the usability of the site for somebody utilizing 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 actually set the mood or set the stage as it were. These graphics are not direct content and may 't be considered essential, but they are essential in that they help frame what is going on.

Attempt to alt-ify the 2nd group as is sensible and it is relevant. There might be times when doing this may be annoying or detrimental with other users. Then avoid it.

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

Most times it depends on context. The same image in a different context may require drastically different alt text. Obviously, content ought to always be fully available. How you use this case is really a judgment call.

III. Content and Function

This is where the image may be the actual content. Always alt-ify content and functional images. Title and long description attributes may also be in order.
The main reason many authors can't understand why their alt text isn't working is they don't know why the pictures exist. You have to figured out exactly what function a picture serves. Consider what it is concerning the image that's important to the page's intended audience.

Every graphic has a reason for being on that page: because it either improves the theme/ mood/ atmosphere or it is advisable to what are the page is attempting to explain. Understanding what the look is perfect for makes alt text simpler to write. And exercise writing them definitely helps.
A method to look into the usefulness of alternative text is to imagine reading the page on the phone to someone. What would you say when encountering a specific image to create the page understandable towards the listener?

Aside from the alt attribute you have a couple more tools available for images.
First, in level 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 not shown like a "tooltip" when focus is received through the keyboard. (So much for device independence). So use the title attribute just for advisory information.
Second, the longdesc attribute points towards the Link to a full description of the image. If the information contained in an image is essential towards the concept of the page (i.e. some important content will be lost when the image was removed), a longer description compared to "alt" attribute can reasonably display should be used. It can 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 the image. As Clark [1] states, "A longdesc is really a long description of an image...The aim is to use any length of description necessary to impart the facts from the graphic.

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

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

In many cases, you are better off just going with your gut instinct -- if it's not necessary to include it, and when you don't have a strong urge to do it, don't include that longdesc.

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

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

The same image may need alt text (or title or longdesc) in one spot, but not in another. If the image provides absolutely no content or functional information alt="" or background CSS images might be appropriate to use. But if the image provides content or adds functional information an alt would be required and maybe a long description would be so as. Oftentimes this kind of thing is really a judgement call.