Friday, April 22, 2011

Alt Attribute & Search engine optimization

SEO Optimization images has become more and more important in SEO (Search Engine Optimization) for websites. The ALT attribute is a critical step that is sometimes forgotten. This can be a lost opportunity for better rankings.

In Google's webmaster guidelines, they advise using alternative text for the images on your 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 have a similar 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, hoping to achieve a particular keyword density, which is not as relevant for rankings now since it was previously.

On the contrary, high keyword density can, on some search engines, trigger spam filters, which might create a penalty for the site's ranking. Even without this type of penalty, your site's rankings won't benefit from this tactic.
This method also puts persons who use screen readers at a greater disadvantage. Screen readers are software-based tools that actually read aloud the contents of what's displayed on the screen. In browsing the web, the alt features of images are read aloud too.

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

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

What used within 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 goal would be to provide the same functional information that a visual user would see. The alt attribute text should be the "stand in" when the image is unavailable. Think about this question: If you were to replace the image using the text, would most users receive the same basic information, and wouldn't it generate the same response?
A few examples:


Some SEO Optimization Tips

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

If an image is supposed to convey the literal items in the look, a description is suitable.

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

If it's meant to convey using 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 merely a decorative role within the page, make use of an empty alt (i.e. alt="") or perhaps a CSS background image so that reading browsers don't bother users by uttering things like "spacer image".

Keep in mind that it's the function of the image we're trying to convey. For instance; any button images shouldn't include the word "button" within the alt text. They ought to emphasize the action performed by the button.

Alt text ought to be determined by context. Exactly the same image in a different context may need drastically different alt text.

Try to flow alt text with the remainder of 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 keep in mind that utilizing 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. Also, they are necessary to meet "Section 508" accessibility requirements in america.

It is important to categorize non-text content into three levels:

Content and Function

I. Eye-Candy

Eye-Candy are stuff that serve no purpose other than 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 some sighted user).

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

Try to alt-ify the 2nd group as is sensible and is relevant. There may be times when doing so may be annoying or detrimental with other users. Then try to avoid it.

For instance; Alt text that is identical to adjacent text is unnecessary, as well as an irritant to screen reader users. I suggest alt="" or background CSS images in such cases. But sometimes, it's vital that you understand this content inside for those users.

Usually it depends on context. The same image inside a different context may require 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 when the look is 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 understand why their alt text isn't working is they don't know why the pictures are there. You need to figured out precisely what function a picture serves. Consider what it is about 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 enhances the theme/ mood/ atmosphere or it is critical to what are the page is attempting to explain. Understanding 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 particular image to make the page understandable to the listener?

Aside from the alt attribute you've got a couple more tools available for images.
First, in level 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 not shown as a "tooltip" when focus is received via the keyboard. (A lot 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 found in an image is essential to the meaning of the page (i.e. some important content would be lost when the image was removed), a longer description than the "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 an image. As Clark [1] states, "A longdesc is really a long description of an image...The aim is by using any length of description essential to impart the facts from the graphic.

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

Even though alt attribute is mandatory for web accessibility as well as for valid (X)HTML, not every images need alternative text, long descriptions, or titles.

Oftentimes, you are better off just choosing your gut instinct -- if it's not essential to include it, and if 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 lot on the function of the image and it is context about the page.

The same image may need alt text (or title or longdesc) in one spot, but not in another. If an 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 would be required and perhaps a long description would be so as. Oftentimes this kind of thing is really a judgement call.

Image Search Engine Optimization Tips

Listed here are key steps in optimizing images:

Choose a logical file name that reinforces the keywords. You can use hyphens in the file name to isolate the keyword, but avoid to exceeding two hyphens. Stay away from underscores as a word separator, such as "brilliant-diamonds.jpg";

Label the file extension. For instance, when the image internet search engine sees a ".jpg" (JPEG) file extension, it's going to assume that the file is really a photo, and if it sees a ".gif" (GIF) file extension, it's going to assume that it is graphic;

Make sure that the text nearby the image that is relevant to that image.
Again, don't lose an excellent chance to help your website with your images in search engines. Use these steps to rank better on all of the engines and drive increased traffic to your site TODAY.

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