caitlinbbsc: 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 sometimes forgotten. This is often a lost chance of better rankings.

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

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

Why would they ask us to achieve that? The answer is easy, really; search engines like google have a similar 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, hoping 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, trigger spam filters, which might result in a penalty for your site's ranking. Even without this type of penalty, your site's rankings will not benefit from this tactic.
This process 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's shown on the screen. In browsing the web, the alt attributes of images are read aloud too.

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

An ALT attribute should not be used like a description or a label to have an image, though many people utilize it in that fashion. Although it may appear natural to assume that alternate text is really 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 exactly the same purpose that the image would.

The thing would be to provide the same functional information that the visual user would see. The alt attribute text should function as a "stand in" when the image itself is unavailable. Think about this: If you were to replace the image with the text, would most users receive the same basic information, and would it generate 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 the image is meant to convey the literal contents of the image, a description is appropriate.

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

If it is designed to convey using a function, then the function 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, use an empty alt (i.e. alt="") or a CSS background image to ensure that reading browsers do not bother users by uttering such things as "spacer image".

Keep in mind that it is the function of 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 through the button.

Alt text should be determined by context. Exactly 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 how it is going to be read with adaptive technologies like screen readers. Someone listening to your page should hardly remember that a graphic image can there be.
Please remember that utilizing an alt attribute for each image is needed to meet the minimum WAI requirements, that are used since the benchmark for accessibility laws in UK and the remainder 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 other than to create a site visually appealing/attractive and (oftentimes) 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 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 the middle layer of graphics which may actually set the atmosphere or set happens so to speak. These graphics aren't direct content and may 't be considered essential, but they're essential in that they help frame what's going on.

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

For example; Alt text that's just like adjacent text is unnecessary, as well as 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 in there for all users.

Most times it depends on context. Exactly the same image inside a different context may require drastically different alt text. Obviously, content should always be fully available. How you use this example is really a judgment call.

III. Content and Function

This is where the look is the actual content. Always alt-ify content and functional images. Title and long description attributes can 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 are there. You have to figured out precisely what function an image serves. Consider what it's concerning the image that's important to the page's intended audience.

Every graphic has a reason behind standing on that page: since it either enhances the theme/ mood/ atmosphere or it is critical to what are the page is attempting to describe. Knowing what the image is for makes alt text easier to write. And exercise writing them definitely helps.
A way to check the usefulness of alternative text would be to imagine reading the page on the phone to someone. An amount you say when encountering a particular image to make 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 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're invisible and never shown as a "tooltip" when focus is received through the keyboard. (So much for device independence). So make use of the title attribute only for advisory information.
Second, the longdesc attribute points towards the Link to a full description of an image. If the information contained in a picture is essential to the meaning of the page (i.e. some important content would be lost when the image was removed), an extended description compared to "alt" attribute can reasonably display should 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 length of description necessary to impart the details from the graphic.

It wouldn't be remiss to hope that a long description conjures an image - the look - in the mind's eye, an analogy that is true even for the totally blind."

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

In many cases, you're better off just choosing 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 include that longdesc.

However, if it's necessary 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 lot about the function of the image and it is 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 absolutely no content or functional information alt="" or background CSS images might be appropriate to make use of. However, if the image provides content or adds functional information an alt will be required and maybe a long description would be in order. Oftentimes this type of thing is a judgement call.