What are alt tags?
Alt tags are associated with an image and, when implemented properly, accurately describe the image. In addition to helping SEO (see next point) alt tags provide useful information to users who may not be able to see the images on a webpage, due to a visual impairment, the use of screen readers or low-bandwidth. Since user experience should be our priority it is important to understand this purpose of alt tags.
On the backend of a webpage an alt tag (alt=) for an image of a red shirt (redshirt.jpg) might look like this:
No alt tag: <img src=”redshirt.jpg” alt=””/>
Alt tag, but not super descriptive: <img src=”redshirt.jpg” alt=” red shirt”/>
Strong alt tag: <img src=”redshirt.jpg” alt=”women’s sheer red silk shirt”>
Why are alt tags important for SEO?
Images are more difficult than text for search engines to understand. As search engines crawl web content, alt tags help them comprehend the images and related webpages. If you include alt tags that follow best practice, you will increase the chance of search engines returning your images in search queries. Why wouldn’t you make it easier for Google to recommend your site to users?
Furthermore, for images that are linked, search engines treat the alt tags similarly to how they treat anchor text in text links. And as you probably know, relevant links contribute to search engine rankings.
Be sure to use alt tags on all of your images, whether they are stock images or original works.
How do you know if your images have alt tags?
feedthebot has a free, handy tool you can use to see if your images have alt tags. This tool follows Google’s best practices for images and tells you:
- image name
- if the image has alt text (it gives a warning if there is no alt tag)
- image dimensions
The analysis of your images is laid out in a simple format.
What should you include in your alt tags?
Search engines want as much information about your image as possible. A strong alt tag will probably contain 4-8 descriptive words, including a keyword or two. Do not get hung up or too focused on including keywords.
If your image is appropriate for your page content then keywords will naturally be a part of your alt tag.
Avoid keyword stuffing your alt tag. Google is good about picking up on this and your site will eventually be marked for spamming.