SEO Optimization images is becoming increasingly more essential in SEO (Seo optimization) for websites. The ALT attribute is a critical step that is often overlooked. This is often a lost chance of better rankings.
In Google's webmaster guidelines, they advise the use of alternative text for the images on your web site:
Images:. Use 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 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, attempting to stuff it with keywords, looking to achieve a certain keyword density, which isn't as relevant for rankings now as it once was.
On the other hand, high keyword density can, on some search engines, trigger spam filters, which might create a penalty for your site's ranking. Even without such a penalty, your site's rankings won't benefit from this plan.
This method also puts persons who use screen readers at a greater disadvantage. Screen readers are software-based tools that really read aloud the items in what's displayed on the screen. In browsing the net, the alt features of images are read aloud as well.
Imagine listening to a paragraph of text which is followed by repetitions of numerous 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 should not be used as a description or a label for 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 is not!
What used inside an image's alt attribute should be its text equivalent and convey the same information or serve the same purpose that the image would.
The goal is to provide the same functional information that a visual user would see. The alt attribute text should be the "stand in" in the event that the look itself is unavailable. Ask yourself this: Should you replace the look using the text, would most users get the same basic information, and would it create the same response?
Some examples:
If a search button is really a magnifying glass or binoculars its alt text should be 'search' or 'find' not 'magnifying glass' or 'binoculars'.
If the image is meant to convey the literal items in the image, then a description is appropriate.
If it's 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 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 don't bother users by uttering things like "spacer image".
Keep in mind that it is the function of the image we are trying to convey. For instance; any button images shouldn't range from the word "button" within the alt text. They ought to 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 rest from the text because that's how it is going to be read with adaptive technologies like screen readers. Someone hearing your page should hardly remember that a graphic image can there be.
Please remember that utilizing an alt attribute for every 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 important 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 might be value to a sighted user).
Never alt-ify eye-candy unless there's something there which 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 actually set the mood or set happens as it were. These graphics aren't direct content and could not be considered essential, but they're important in they help frame what's going on.
Try to alt-ify the 2nd group as makes sense and it is relevant. There may be times when doing so might be annoying or detrimental with 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 vital that you understand 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. How you go in this example 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 can also be so as.
The main reason many authors can't understand why their alt text isn't working is that they don't know why the images are there. You need to figured out exactly what function a picture serves. Think about 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: because it either improves the theme/ mood/ atmosphere or it is advisable to what are the page is trying to explain. Knowing what the image is for makes alt text simpler to write. And exercise writing them definitely helps.
A method to look into the usefulness of alternative text would be to imagine reading the page over the telephone to someone. An amount you say when encountering a specific image to make the page understandable to the listener?
Aside from the alt attribute you have a couple more tools at your disposal 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 through the user agent. Remember they are invisible and never shown as 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 Link to a complete description of an image. If the information found in a picture is important to the meaning of the page (i.e. some important content would be lost when the image was removed), an extended description than the "alt" attribute can reasonably display ought to be used. It may offer rich, expressive documentation of a visual image.
It ought to 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 length of description essential to impart the facts of the graphic.
It wouldn't be remiss to hope that the long description conjures a picture - the look - in the mind's eye, an analogy that is true even for that totally blind."
Although the alt attribute is mandatory for web accessibility as well as for valid (X)HTML, not every images need alternative text, long descriptions, or titles.
In many cases, you're best just going with your gut instinct -- if it's not necessary to include it, and when you don't possess a strong urge to get it done, don't add that longdesc.
However, if it's essential for the entire page to work, then you've to add the alt text (or title or longdesc).
What's necessary and what's not depends a lot about the function of your image and its context about the page.
Exactly the same image may need alt text (or title or longdesc) in a single spot, but not in another. If the image provides simply no content or functional information alt="" or background CSS images might be appropriate to use. But 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 a judgement call.
Listed below 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 example, if the image search engine sees a ".jpg" (JPEG) file extension, it's going to assume that the file is really a photo, and when it sees a ".gif" (GIF) file extension, it's going to assume that it is a graphic;
Make sure that the written text at the image that's highly relevant to that image.
Again, don't lose a great chance to help your site together with your images searching engines. Begin using these steps to position better on all the engines and drive increased traffic to your site TODAY.
Peter Risdon Says:
May 16, 2011 at 2:40 pm | Reply
The paragraph you quoted from ends with this sentence:
“According to the best-sited stations, the diurnal temperature range in the lower 48 states has no century-scale trend.”
That was a surprise given the tenor of this post: “… maybe this is the end to questions as to whether surface temperature increases actually exist.”
Did you mean that we can now say the answer to that is that surface temperature increases do not exist? Or that, pace Keenan in the WSJ, the data do not contain statistically significant trends?
andyrussell Says:
May 16, 2011 at 2:58 pm | Reply
I don’t think diurnal temperature range is very important. Do you?
What’s more, the “century-scale” bit covers some interesting detail. Before Fall et al., it seems that the only work on diurnal temperature range showed a negative trend from the mid-century to 1980s-ish. What Fall et al. found was that this has increased again since the 1980s. So there’s no “century-scale trend”.
But that tells you very little about mean surface temperature trends.
Mark Says:
May 17, 2011 at 10:45 pm
I have heard it claimed that the reduction in diurnal temperature range over the past few decades provides evidence that GHG increases are responsible for the warming. In that sense, some people think diurnal temperature range is important.
Incidentally, I don’t think Fall et al. were the first to find that DTR has increased since the 1980s. I read a paper that said much the same thing a few years ago.
Sorry for the lack of references to back up these statements. I’m a little too busy at the moment to chase them up.
Ben Says:
May 16, 2011 at 4:49 pm | Reply
So Peter… If the diurnal high and the diurnal low both rise by 1°C, you think this means there has been no warming? After-all, the diurnal range hasn’t changed! Others might draw a different conclusion.
Peter Risdon Says:
May 17, 2011 at 8:26 am | Reply
I understand diurnal range has significance, and the relationship between day and night time temperature ranges is important, especially with regard to the period 1950 to 1980 when the effect of man-made global warming, it has been argued, was masked by a cooling but revealed by the changes in the relationship between these ranges.
I further understand that this argument is based on the idea that human pollution caused this daytime cooling, that it affected the range of day time temperatures as well as the difference between night time temperatures which continued to show warming, and daytime ones that didn’t. This makes day time temperature range significant: if this is right it would be expected to show a variation that correlates with human activity.
But this isn’t my field; I’m just reading what I can in an attempt to understand as much as possible about an important issue and, for me at least, that means reading Watts and reading this blog. Just searching out stuff you’re already disposed to accept isn’t good enough. My comment was prompted by what struck me as a somewhat partial quotation and exasperation: I’m with Feynman when he said you should point out the problems with a theory, not just the things that support it.
[It's not really a "partial quotation" is it? That sentence you are interested in is stuck on the end of the abstract as a new paragraph and isn't really related to the 2 sentences I quote and which are related to the subject of this post. I'm not really interested in DTR and I doubt Watts was either. - AR]
At least Watts invites people with different views to post on his blog and has been at the forefront of attempts to cross the ideological divide, not least with Judith Curry.
Ben, of course you’re right. Andy, a century is an arbitrary scale, of course.
I’d still be interested in your take on statistical significance.
JMurphy Says:
May 17, 2011 at 12:05 pm | Reply
In what way has Watts atempted to cross “the ideological divide” ?
Ben Says:
May 17, 2011 at 3:16 pm | Reply
Peter, I encourage a critical (i.e. thoughtful) reading of Anthony’s blog but my god do you really think he’s “at the forefront of attempts to cross the ideological divide”? Anthony has done more to harden denialist thought than anyone, with the possible exception Marc Morano.
The “different views” he solicits are unthreatening fig-leaves.
andyrussell Says:
May 17, 2011 at 3:24 pm | Reply
I’ve got no problem with most of what Keenan says, although he’s not the first/only person to be saying these things. There’s a JoC paper from 2010 and it was one of the useful points to come out of the UEA email enquiries (i.e. working more with stats people). Not sure where the funding was supposed to come from for these new people though!
I suppose the bigger problem comes down to climate science covering so much stuff – you can’t just look at problems from a stats/dynamics/modelling/chemistry/radiation/whatever perspective for too long before a) not getting very far or b) needing to doing something you’ve not done before.