About Me 0106: Alt Attribute & Search engine optimization

SEO Optimization images is becoming increasingly 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 web site:

Images:. Make use of the alt attribute to provide descriptive text. Additionally, 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 can't 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 is not as relevant for rankings now since 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 the site's ranking. Even without such a penalty, your site's rankings will not benefit from this plan.
This method 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's shown 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 would be not even close to accessible, and, to put it bluntly, will be found quite annoying.
What is an Alt attribute?

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

What used inside an image's alt attribute should be its text equivalent and convey exactly the same information or serve exactly 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" in the event that the look is unavailable. Ask yourself this question: If you were to replace the look with the text, would most users receive 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 should be 'search' or 'find' not 'magnifying glass' or 'binoculars'.

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

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

If it is designed to convey using 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 as well as for valid XHTML.

For images that play only a decorative role within the page, make use of an empty alt (i.e. alt="") or a CSS background image to ensure that reading browsers do not bother users by uttering things like "spacer image".

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

Alt text should be determined by context. Exactly the same image inside a different context may need drastically different alt text.

Try to flow alt text with the remainder from 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 satisfy the minimum WAI requirements, that are used as the benchmark for accessibility laws in UK and also the remainder of Europe. They are also required to meet "Section 508" accessibility requirements in america.

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 other than to create 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 some sighted user).

Never alt-ify eye-candy unless there's something there which will enhance the usability from the site for someone using 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 actually the middle layer of graphics which may actually set the atmosphere or set the stage so to speak. These graphics aren't direct content and could 't be considered essential, but they're essential in they help frame what is going on.

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

For instance; 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 understand this content inside for those users.

Most times this will depend on context. The same image inside a different context may need drastically different alt text. Obviously, content ought to always be fully available. How you go in 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 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 pictures are there. You need 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 includes a reason for standing on that page: because it either enhances the theme/ mood/ atmosphere or it is advisable to what are the page is attempting to explain. Understanding what the image is perfect for makes alt text easier to write. And practice 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. 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 degree 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're invisible and never shown like a "tooltip" when focus is received via the keyboard. (So much for device independence). So use the title attribute just for advisory information.
Second, the longdesc attribute points towards the URL of a full description of the image. When the information contained in a picture is essential towards the meaning 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 should 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 the image...The goal is by using any length of description essential to impart the details of the graphic.

It wouldn't be remiss to hope that the 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.

In many cases, you're best just choosing your gut instinct -- if it's not essential to incorporate it, and if you don't have a strong urge to get it done, don't add that longdesc.

However, if it's necessary for the entire 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 about the function of your image and its context on the page.

The same image may need alt text (or title or longdesc) in a single spot, although not in another. If an image provides simply 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 will be required and maybe a long description will be in order. In many cases this type of thing is really a judgement call.