About Me 0067: Alt Attribute & SEO Optimization

SEO Optimization images is becoming increasingly more essential in SEO (Search Engine Optimization) for websites. The ALT attribute is a critical step that is sometimes forgotten. This is often a lost opportunity for better rankings.

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

Images:. Make use of the alt attribute to supply 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 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, trying to stuff it with keywords, looking to achieve a certain keyword density, which isn't as relevant for rankings now as it was previously.

On the contrary, high keyword density can, on some search engines like google, trigger spam filters, which might 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 in a greater disadvantage. Screen readers are software-based tools that really read aloud the contents of what is shown on the screen. In browsing the net, the alt attributes of images are read aloud as well.

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

An ALT attribute should not be used as a description or a label to have an image, though lots of people utilize it in that fashion. Although it might seem natural to assume that alternate text is a label or perhaps a description, it's not!

What used inside 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 goal 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 image is not available. Think about this question: If you were to replace the image with the text, would most users get the same basic information, and would it generate the same response?
Some examples:

Some SEO Optimization Tips

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

If an image is meant to convey the literal items in the image, then a description is appropriate.

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

If it's meant to convey the use of a function, then your function itself 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, use an empty alt (i.e. alt="") or perhaps a CSS background image to ensure that reading browsers don't bother users by uttering such things as "spacer image".

Keep in mind that it is the function of the image we're attempting to convey. For example; any button images should not range from the word "button" in the alt text. They should emphasize the action performed through the button.

Alt text ought to be based on context. The same image in a different context may require 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 listening to your page should hardly remember that a graphic image is there.
Please remember that using an alt attribute for each image is needed to satisfy the minimum WAI requirements, which are used as the benchmark for accessibility laws in UK and the rest of Europe. They are also 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 (in many cases) fulfill the marketing departments. There is no content value (though there may be value to a sighted user).

Never alt-ify eye-candy unless there's something there that will enhance 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 may actually set the atmosphere or set happens as it were. These graphics are not direct content and may not be considered essential, but they are important in that they help frame what is going on.

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

For example; Alt text that is 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 important to get this content inside for those users.

Most times it depends on context. Exactly 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 a judgment call.

III. Content and Function

This is where the look may be the actual content. Always alt-ify content and functional images. Title and long description attributes may also be in order.
The reason many authors can't figure out why their alt text isn't working is that they don't know why the images exist. You need to figured out exactly what function a picture serves. Think about what it is concerning the image that's important to the page's intended audience.

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

Besides 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 can add flavor. The title attribute is optionally rendered through the user agent. Remember they're invisible and not shown like a "tooltip" when focus is received through the keyboard. (A lot for device independence). So use the title attribute just for advisory information.
Second, the longdesc attribute points to the URL of a full description of an image. When the information found in a picture is essential towards the concept of the page (i.e. some important content will be lost if the image was removed), an extended description than the "alt" attribute can reasonably display should be used. It may offer 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 really a long description of the image...The goal is to use any length of description necessary to impart the details of the graphic.

It wouldn't be remiss to hope that a long description conjures an image - the image - within 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 every images need alternative text, long descriptions, or titles.

Oftentimes, you are better off just going with your gut instinct -- if it's not necessary to include it, and when 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 work, then you have to include the alt text (or title or longdesc).

What's necessary and what's not depends a great deal on the function of the image and it is 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 absolutely no content or functional information alt="" or background CSS images may be appropriate to make use of. But if the image provides content or adds functional information an alt would be required and maybe even a long description will be so as. In many cases this type of thing is a judgement call.