For web marketing training, presentations and workshops visit Pacifica Training. If you wish to ask questions about website marketing please head over and register free at the website marketing forum, a knowledge base and community driven discussion group.
Alt Tags
Published: August 14, 2006
alt tags represent alternative text for a non text element. The most common use of alt is within the image element but before we start there is one point to make.
alt is not a tag, it's an attribute.
Now we have cleared that up, take a look at the structure of the code that includes an alt attribute.
<img width="100" height="100" src="tn38logo.jpg" alt="TN38 Internet">
The above HTML code draws an image and uses the img element. The alt attribute is, well, an attribute of the img element.
What's the alt tag, sorry, attribute good for?
Primarily, it's a feature for the consumption of non text elements like images. If, for whatever reason, an image cannot be displayed, seen or recognised then there is a text alternative to help the consumer understand what the image or other non text element represents.
Instead of looking at the recommended use of this attribute [good article here], we'll cover the most abused area of this attribute.
alt and search engines
Search engines are as valid a consumer as people because they do most of the serving to people and we need to ensure that our websites are marked up well, abide by the web standards and are search engine friendly.
Now, how does the alt attribute assist us in the search engines?
First of all, the biggest sin of all: keyword stuffing. Because the text in an alt attribute doesn't get rendered, or if it does it doesn't occupy more space than the image placeholder, it's tempting to put every keyword going into it. However, this does more harm than good.
Keyword stuffing an alt attribute increases the keyword density of the page and this lowers it's 'readability' [read: quality]. If the page quality suffers, so will the search engine results you're aiming for. The alt attribute needs to accurately describe the image, it's context and purpose. This needs to be as concise as possible and takes some consideration. Ask yourself, if you couldn't see the image, would the text inform you sufficiently as to the images meaning?
The easiest alt attributes to write are the ones where images convey textual information as you can successfully duplicate that text. Job done! But what about photos, symbols and other visual gestures? These require an understanding of the intended message to the user and a short few keywords to sum it up.
It's tempting to put keywords in the alt attribute but the key is to consider the fact that if the non text element isn't part of the information on the page, what's it doing there? Remember, pages must be focused and we have no room for off topic information. By following that most fundamental of rules, we ensure we can safely apply a relevant alt attribute to our images.
Does the alt attribute help with the search engines
From experience, I would say not to any discernable degree. The problem with the alt attribute is that it is a property of another element and not a primary element itself. This effectively lowers it's value compared to say, a paragraph or a header. The alt attribute doesn't convey any hierarchical information like headers do and since it's job is assistive and not primary, it's value will reflect that.
Now what?
Take this as a cue to go back over your images, check to see if you have the alt attributes in the first place, then write them as nature intended, to inform the user the meaning of the image. Instead of keyword stuffing, ensure the image is relevant to the topic of the page then you've got the perfect excuse to put a keyword in the alt attribute haven't you!
Useful?
Assistance?
Comments
Ocira says:
Alex says:
We are forgetting the main purpose of alt tags - Web accessibility. People with problems use browsers which read these alt tags.
From SEO point of view, keyword stuffing was modern a few years ago but the search engines adjust to that technique.
In the article you missed one more SEO benefit of alt tags - traffic from search engine image search. Alt tags in images help the search engine to "see" what the image is about.
Well put indeed. The alt attribute is so important when using text only browsers like lynx or even when common browsers are running on a slow internet link and the image delays to display or does not display at all. The alt tag informs the user on what image or graphic is supposed to display where the alt attribute is.
So basically the alt attribute has to be short and precise.