About Me 0049: Alt Attribute & SEO Optimization

SEO Optimization images has become increasingly more essential in SEO (Search Engine Optimization) for websites. The ALT attribute is 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 the images on your web site:

Images:. Use 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 like google 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, trying 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, trigger spam filters, which may create a penalty for your site's ranking. Even without this type of penalty, your site's rankings will not 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 contents of what's 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 many keywords. The page will be far from accessible, and, to put it mildly, will be found quite annoying.
What exactly is an Alt attribute?

An ALT attribute shouldn't 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 really a label or a description, it is not!

What 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 would be 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 itself 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 would it create the same response?
A few examples:

Some SEO Optimization Tips

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

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

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

If it is meant 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 and for valid XHTML.

For images that play merely a decorative role in the page, use an empty alt (i.e. alt="") or perhaps 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's the function of the image we're attempting to convey. For instance; 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 ought to be based on context. The same image in a different context may need drastically different alt text.

Try to flow alt text with the rest from 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 remember that a graphic image is there.
Please remember that utilizing an alt attribute for every image is needed to satisfy the minimum WAI requirements, that are used since the benchmark for accessibility laws in UK and the remainder of Europe. They are also required to meet "Section 508" accessibility requirements in the US.

It is useful 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 make a site visually appealing/attractive and (in many cases) fulfill the marketing departments. There isn't any content value (though there may be value to some sighted user).

Never alt-ify eye-candy unless there is something there that will boost 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 the middle layer of graphics which may serve to set the mood or set the stage as it were. These graphics are not direct content and could 't be considered essential, but they're important in they help frame what's going on.

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

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

Most times this will depend 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 case is really 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 in order.
The main reason many authors can't figure out why their alt text isn't working is that they don't know why the images are there. You need to determined precisely what function a picture serves. Consider what it is concerning the image that's vital that you the page's intended audience.

Every graphic has a reason for being on that page: since it either improves the theme/ mood/ atmosphere or it is advisable to what the page is attempting to explain. Knowing what the look is perfect for makes alt text simpler to write. And exercise writing them definitely helps.
A method to check the usefulness of alternative text is to imagine reading the page on the phone to someone. What would you say when encountering a specific image to create the page understandable to the listener?

Besides the alt attribute you've got a couple more tools available for images.
First, in level of descriptiveness title is in between alt and longdesc. It adds useful information and can add flavor. The title attribute is optionally rendered by the user agent. Remember they're invisible and not shown as a "tooltip" when focus is received via the keyboard. (A lot for device independence). So use the title attribute only for advisory information.
Second, the longdesc attribute points to the URL of a complete description of an image. When the information found in an image is important to the concept 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 ought to be used. It can 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 the image. As Clark [1] states, "A longdesc is a long description of the image...The aim is to use any period of description necessary to impart the details of the graphic.

It would not be remiss to hope that the long description conjures an image - the look - within the mind's eye, an analogy that is true even for that 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 essential to include it, and when you don't have a strong urge to do it, don't include that longdesc.

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

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