About Me 0062: Alt Attribute & Search engine 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 using alternative text for that images in your site:

Images:. Make use of the alt attribute to supply descriptive text. In addition, we recommend utilizing a human-readable caption and descriptive text around the image.

Why would they ask us to do that? The answer is simple, really; search engines 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, attempting to stuff it with keywords, hoping to achieve a certain keyword density, which is not as relevant for rankings now since it was previously.

On the other hand, high keyword density can, on some search engines like google, trigger spam filters, which may result in a penalty for your site's ranking. Even without such a penalty, your site's rankings will not take advantage of this plan.
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 displayed on the screen. In browsing the web, the alt features of images are read aloud too.

Imagine hearing a paragraph of text that is followed by repetitions of numerous keywords. The page will be not even close to accessible, and, to put it mildly, would be found quite annoying.
What exactly is an Alt attribute?

An ALT attribute shouldn't be used as a description or perhaps a label for an image, though many people use it for the reason that fashion. Although 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 the same information or serve the same purpose that the image would.

The goal is 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 image itself is not available. Think about this: If you were to replace the image 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 should be 'search' or 'find' not 'magnifying glass' or 'binoculars'.

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

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

If it is meant to convey using a function, then your function itself is what should 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 a CSS background image so that reading browsers do not bother users by uttering such things as "spacer image".

Remember that it is the function from the image we are attempting to convey. For instance; any button images shouldn't range from the word "button" in the alt text. They should emphasize the action performed through the button.

Alt text ought to be determined by context. The same image inside a different context may require drastically different alt text.

Try to flow alt text with the rest of the text because that's the way 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 can there be.
Please keep in mind that using 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 (oftentimes) fulfill the marketing departments. There is no content value (though there might be value to a sighted user).

Never alt-ify eye-candy unless there's something there which will enhance the usability of the site for someone 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 might actually set the mood or set happens so to speak. These graphics are not direct content and may not be considered essential, but they are important in they help frame what's going on.

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

For instance; Alt text that's just like 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 understand this content inside for those users.

Usually 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 use this case is a judgment call.

III. Content and Function

This is when 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 determined precisely what function an image serves. Consider what it's about the image that's vital that you the page's intended audience.

Every graphic includes a reason behind being on that page: because it either improves the theme/ mood/ atmosphere or it is critical to what the page is attempting to describe. Knowing what the image 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 would be to imagine reading the page on the phone to someone. What would you say when encountering a particular image to create the page understandable towards the listener?

Aside from the alt attribute you have a couple more tools at your disposal for images.
First, in degree 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 are 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 to the Link to a full description of an image. If the information contained in a picture is essential to the concept 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 ought to be used. It can 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 an image...The aim is to use any period of description necessary to impart the facts from the graphic.

It would not be remiss to hope that the long description conjures an image - 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 and for valid (X)HTML, not all images need alternative text, long descriptions, or titles.

Oftentimes, you're better off just going with your gut instinct -- if it's not essential to include it, and if you don't have a strong urge to get it done, don't add that longdesc.

However, if it's essential for the entire page to operate, then you've to add 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 about the page.

The same image may need alt text (or title or longdesc) in one spot, although not in another. If an image provides simply no content or functional information alt="" or background CSS images may be appropriate to make use of. However, 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 really a judgement call.