About Me 0060: Alt Attribute & Search engine optimization

SEO Optimization images has become increasingly more important in SEO (Seo optimization) for websites. The ALT attribute is really a critical step that is often overlooked. This can be a lost chance of better rankings.

In Google's webmaster guidelines, they advise using alternative text for the images in 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 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, hoping to achieve a particular keyword density, which is not 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 such a penalty, your site's rankings won't take advantage of this tactic.
This process also puts persons who use screen readers in a greater disadvantage. Screen readers are software-based tools that really read aloud the items in what is shown on the screen. In browsing the web, 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 would be far from accessible, and, to put it mildly, will be found quite annoying.
What exactly is an Alt attribute?

An ALT attribute should not be used like a description or perhaps a label for an image, though lots of people utilize it in that fashion. Although it might seem natural to assume that alternate text is a label or a description, it's not!

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

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

Some SEO Optimization Tips

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

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

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

If it's meant to convey the use of a function, then your function is what ought to 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, make use of an empty alt (i.e. alt="") or perhaps a CSS background image so that reading browsers do not bother users by uttering things like "spacer image".

Remember that it's the function from the image we are attempting to convey. For instance; any button images should not include the word "button" within the alt text. They should emphasize the action performed by the button.

Alt text ought to be determined by 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 is going to be read with adaptive technologies like screen readers. Someone listening to your page should hardly be aware that a graphic image is there.
Please remember that using an alt attribute for every image is required to meet the minimum WAI requirements, that are used since the benchmark for accessibility laws in UK and the rest of Europe. They are also necessary to meet "Section 508" accessibility requirements in the US.

It is important 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 may be value to a sighted user).

Never alt-ify eye-candy unless there's something there which will boost the usability of the site for somebody 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 atmosphere or set happens so to speak. These graphics aren't direct content and may not be considered essential, but they're essential in they help frame what's going on.

Attempt to alt-ify the second group as makes sense and it is relevant. There may be times when doing so may be annoying or detrimental with 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 recommend alt="" or background CSS images in such instances. But sometimes, it's important to understand this content inside for those 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. The way you go in this example is really a judgment call.

III. Content and Function

This is when the look is 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 figure out why their alt text isn't working is they don't know why the pictures exist. You have to determined exactly what function an image serves. Consider what it's about the image that's vital that you the page's intended audience.

Every graphic has a reason behind standing on that page: because it either enhances the theme/ mood/ atmosphere or it is advisable to what are the page is trying to describe. Understanding what the image is for makes alt text easier to write. And exercise writing them definitely helps.
A way to look into the usefulness of alternative text would be to imagine reading the page over the telephone to someone. An amount you say when encountering a specific image to make the page understandable to the listener?

Aside from the alt attribute you've got a couple more tools available for images.
First, in degree of descriptiveness title is in 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 as a "tooltip" when focus is received through the keyboard. (A lot for device independence). So make use of 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 contained in an image is important towards the concept of the page (i.e. some important content will be lost if the image was removed), an extended 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 the image...The aim is by using any length of description essential to impart the details of 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 that totally blind."

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

Oftentimes, you are better off just going with your gut instinct -- if it's not necessary to incorporate it, and when you don't possess 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've to include the alt text (or title or longdesc).

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

The same image may require alt text (or title or longdesc) in one spot, but not in another. If an 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 even a long description will be so as. Oftentimes this kind of thing is a judgement call.