About Me 0079: Alt Attribute & Search engine 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 sometimes forgotten. This can be a lost chance of better rankings.

In Google's webmaster guidelines, they advise using alternative text for that images in your web site:

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

Why would they ask us to do that? The answer is simple, 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 particular 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 won't take advantage of this tactic.
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 hearing a paragraph of text that is followed by repetitions of numerous keywords. The page would be far from 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 a label for an image, though lots of people use it in that fashion. Though it may appear 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 the image would.

The thing is to supply the same functional information that the visual user would see. The alt attribute text should function as a "stand in" in the event that the image is not available. Think about this question: Should you replace the look using the text, would most users get the same basic information, and would it create the same response?
A few 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 an image is meant to convey the literal contents of the look, a description is suitable.

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

If it is designed to convey the use of a function, then your 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 in 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 from the image we're trying to convey. For instance; any button images should not range from the word "button" in the alt text. They should emphasize the action performed by the button.

Alt text should be based on context. Exactly the same image in a different context may need drastically different alt text.

Attempt 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 hearing your page should hardly remember 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 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 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 is something there which will boost the usability of 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 might serve to set the mood or set the stage as it were. These graphics are not direct content and may 't be considered essential, but they are important in they help frame what's going on.

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

For instance; Alt text that's identical to adjacent text is unnecessary, and an irritant to screen reader users. I suggest alt="" or background CSS images in such cases. But sometimes, it's important to get this content inside for all users.

Most times it depends on context. The same image in a different context may need drastically different alt text. Obviously, content should always be fully available. The way 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 determined exactly what function an image serves. Think about what it's about the image that's important to the page's intended audience.

Every graphic includes 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 trying to describe. Knowing what the image is perfect for makes alt text easier to write. And exercise writing them definitely helps.
A way to look into the usefulness of alternative text is to imagine reading the page on the phone to someone. An amount 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 available 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're invisible and never shown as a "tooltip" when focus is received through 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 an image. When the information found in a picture 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 may 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 image - in 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 are best just choosing your gut instinct -- if it's not essential to incorporate it, and if you don't have a strong urge to do it, don't include that longdesc.

However, if it's necessary for the whole page to work, then you have 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 its context on the page.

The same image may need alt text (or title or longdesc) in a single spot, but not in another. If an image provides absolutely no content or functional information alt="" or background CSS images may be appropriate to use. But if the image provides content or adds functional information an alt will be required and maybe a long description will be so as. Oftentimes this type of thing is a judgement call.