Matt Cutts recently produced a video explaining how Google looks at the alt attribute on an image tag and offers some good tips for how best to use them.
- Search engines have a hard time understanding the subject of an image
- You can help search engines by adding descriptive text to the alt attribute of an image
- Do not stuff alt attributes with keywords
- Give your images meaningful names
I want to add a few more thoughts on the use of an alt attribute. First alt is an attribute of the image tag and not a tag itself. I doubt the term alt tag is ever going to go away, but there is no
<img src="name-of-your-image.jpg" alt="description of your image" width="200px" height="100px" />
It may seem somewhat semantic to make this distinction and in reality it’s more important to use the attribute properly than worry about whether it is technically a tag or an attribute, but since writing good code is important to me I wanted to mention it.
If your image is also a link you might want to add an additional title attribute, which would describe the content you would find after clicking the link. You would add the title attribute to the link tag and not the image tag.
Again these attributes aren’t anything you should stuff full of keywords. They are part of basic on page seo, but think of them with accessibility in mind first. Imagine a person who can’t see your image and write something to describe the image for that person and not specifically for a search engine. Your alt attribute need only be a few words, but if for some reason you feel a simple sentence isn’t enough use the longdesc attribute of the image instead (longdesc=”longer description of your image”).
Images are an often overlooked part of search engine optimization, but image search can be a good source of traffic. If you follow the basics Matt mentions in the video and give your images descriptive names and use an alt attribute on those images you’ll probably find traffic from Google image search in your log files.
If you’d like to get a little more advanced with your image optimization here are a few additional sources to get you started.