About Me 0105: Alt Attribute & SEO Optimization

SEO Optimization images is becoming more and more essential in SEO (Search Engine Optimization) for websites. The ALT attribute is really 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 the images on your site:

Images:. Make use of 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 achieve that? The answer is simple, really; search engines like google have a similar problem as blind users. They cannot 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 certain keyword density, which isn't as relevant for rankings now since it was previously.

On the contrary, high keyword density can, on some search engines, trigger spam filters, which might create a penalty for the site's ranking. Even without this type of penalty, your site's rankings won't take advantage of this tactic.
This method also puts persons who use screen readers at a greater disadvantage. Screen readers are software-based tools that really read aloud the items in what is displayed on the screen. In browsing the net, the alt attributes of images are read aloud too.

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

An ALT attribute shouldn't be used as a description or a label to have an image, though many people use it for the reason that fashion. Although it might seem natural to assume that alternate text is a label or a description, it's not!

What 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 supply the same functional information that the visual user would see. The alt attribute text should be the "stand in" in the event that the look itself is not available. Ask yourself this: If you were to replace the look with the text, would most users receive the same basic information, and would it create the same response?
Some examples:

Some SEO Optimization Tips

If your search button is really a magnifier 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 contents of the image, then a description is suitable.

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

If it is designed to convey the use of a function, then the function 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 within the page, make use of an empty alt (i.e. alt="") or perhaps a CSS background image to ensure that reading browsers don't bother users by uttering things like "spacer image".

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

Alt text ought to be based on context. Exactly 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 the way it will be read with adaptive technologies like screen readers. Someone listening to your page should hardly be aware that a graphic image is there.
Please keep in mind that utilizing an alt attribute for every image is needed to satisfy the minimum WAI requirements, which are used since the benchmark for accessibility laws in UK and the rest of Europe. Also, they are 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 apart from to make a site visually appealing/attractive and (in many cases) fulfill the marketing departments. There isn't any content value (though there might be value to a sighted user).

Never alt-ify eye-candy unless there is something there which 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 the middle layer of graphics which might actually set the mood or set the stage as it were. These graphics are not direct content and may not be considered essential, but they're important in they help frame what's going on.

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

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

Most times this will depend on context. Exactly the same image in a different context may require drastically different alt text. Obviously, content should always be fully available. How you go in this case is a judgment call.

III. Content and Function

This is when the look may be the actual content. Always alt-ify content and functional images. Title and long description attributes can also be so as.
The main 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 precisely what function a picture serves. Consider what it's concerning the image that's important to the page's intended audience.

Every graphic has a reason behind being on that page: because it either enhances the theme/ mood/ atmosphere or it is advisable to what are the page is attempting to describe. Knowing what the image is perfect for makes alt text easier to write. And exercise writing them definitely helps.
A method to check the usefulness of alternative text would be 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?

Besides 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 through the user agent. Remember they are invisible and not shown like a "tooltip" when focus is received via the keyboard. (A lot for device independence). So use the title attribute just for advisory information.
Second, the longdesc attribute points to the Link to a complete description of an image. When the information found in a picture is important to the concept of the page (i.e. some important content will be lost if the image was removed), an extended description than the "alt" attribute can reasonably display ought to be used. It may provide for rich, expressive documentation of a visual image.

It should 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 the image...The aim is by using any period of description necessary to impart the details from the graphic.

It wouldn't be remiss to hope that a long description conjures a picture - the look - within the mind's eye, an analogy that holds true even for the 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 are best just going with your gut instinct -- if it's not essential to include it, and when you don't possess 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 include the alt text (or title or longdesc).

What's necessary and what's not depends a great deal on the function of the 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 simply no content or functional information alt="" or background CSS images may be appropriate to make use of. But if the image provides content or adds functional information an alt would be required and maybe even a long description will be so as. In many cases this kind of thing is a judgement call.