About Me 0129: Alt Attribute & Search engine optimization

SEO Optimization images has become more and more essential in SEO (Search Engine Optimization) for websites. The ALT attribute is a critical step that is often overlooked. This can be a lost chance of better rankings.

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

Images:. Make use of the alt attribute to provide descriptive text. Additionally, we recommend utilizing 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 the same problem as blind users. They cannot 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 since it was previously.

On the contrary, high keyword density can, on some search engines, 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 benefit from this tactic.
This method also puts persons who use screen readers in a greater disadvantage. Screen readers are software-based tools that actually read aloud the contents of what is 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, would be found quite annoying.
What exactly is an Alt attribute?

An ALT attribute shouldn't be used as a description or a label to have an image, though many people utilize it for the reason that fashion. Though it may appear 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 exactly the same information or serve the same purpose that the image would.

The thing is 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 is not available. Ask yourself this: If you were to replace the image using the text, would most users get the same basic information, and wouldn't it create the same response?
Some 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 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 is meant to convey the use of a function, then your function 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 merely a decorative role within the page, use an empty alt (i.e. alt="") or a CSS background image to ensure that reading browsers don't bother users by uttering such things as "spacer image".

Remember that it is the function of the image we are attempting 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 ought to be based on context. The same image inside a different context may require drastically different alt text.

Try to flow alt text with the rest from the text because that's how it will be read with adaptive technologies like screen readers. Someone hearing your page should hardly be aware that a graphic image can there be.
Please remember that utilizing an alt attribute for each image is required to meet the minimum WAI requirements, which 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 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 create a site visually appealing/attractive and (oftentimes) 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 from the site for somebody using 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 may serve to set the atmosphere or set the stage so to speak. These graphics aren't direct content and could 't be considered essential, but they're essential in they help frame what's going on.

Try to alt-ify the second group as is sensible and it is relevant. There may be instances when doing this might be annoying or detrimental with other users. Then try to 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 vital that you understand this content in there for all users.

Most times this will depend on context. Exactly the same image inside a different context may need 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 look is the actual content. Always alt-ify content and functional images. Title and long description attributes may also be so as.
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 exist. You have to determined precisely what function an image serves. Think about 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: because 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 perfect for makes alt text simpler to write. And exercise writing them definitely helps.
A method to check 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?

Besides the alt attribute you have a couple more tools at your disposal 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 are invisible and not shown like a "tooltip" when focus is received via the keyboard. (A lot for device independence). So make use of the title attribute just for advisory information.
Second, the longdesc attribute points to the Link to a complete description of the image. When the information found in an image is essential towards the meaning 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 should be used. It can provide for rich, expressive documentation of a visual image.

It ought to be used when alt and title are insufficient to embody the visual qualities of an image. As Clark [1] states, "A longdesc is a long description of an image...The goal is to use any period of description essential to impart the details from the graphic.

It wouldn't be remiss to hope that the long description conjures a picture - the image - within the mind's eye, an analogy that holds true even for the 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 going with your gut instinct -- if it's not essential to incorporate it, and when 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 have to include 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 on the page.

Exactly the same image may require alt text (or title or longdesc) in one spot, but not in another. If an image provides simply no content or functional information alt="" or background CSS images may be appropriate to use. However, if the image provides content or adds functional information an alt would be required and perhaps a long description will be in order. Oftentimes this kind of thing is really a judgement call.