ALT tags are used to provide text based information about images on your website. The ALT tag of an image can be seen by hovering over it with your mouse, or by looking in the code of a page. Often if an image doesn’t load (due to a connection issue or broken link) the ALT tag is shown in the space where the image should be displayed; on screen readers for people with visual impairments the ALT tag is read out to allow them to enjoy your website design as much as anyone else.
Are ALT tags important to SEO?
Both Google and Bing use ALT tags to provide ranking information BUT it’s important to note that the majority of these benefits are for image related searches.
Keyword stuffed ALT tags are just as bad for your SEO as it is to have keywords stuffed into the actual content on your page. So before you think it’s a good idea for you to just place the keyword for a page in the ALT tags on that page, give a bit of thought to what that will do to your page. It’s better to consider something which explains the image, perhaps a location or if it’s a product image then the name of the product.
People with screen readers should be a focus for your work with ALT tags. Providing useful, meaningful descriptions of images is much more important to them than it is to ensure all your images have a keyword rich ALT tag.
Other things to consider with Images
Optimising your website and running a site which is rich in image based content is about more than just the alt tags.
If you do run a website which is heavily led by images – such as an online shop – and you want to make the most of your images from an SEO point of view, then you need to consider how you promote them.
Include an image sitemap onto your site
Make sure that your images are named in a consistent method. Even the file names can help you along the way. So don’t call your images 12345.jpg. It’s best to use hyphens to split words up rather than underscores, pluses or having the file name run into one. It’s also a good idea to make sure the image names don’t spam your keyword, so having 100 images called blue-widget-1.jpg, blue-widget-2.jpg, blue-widget-3.jpg, blue-widget-4.jpg, etc. won’t help at all.
Back from my days as a developer I also recommend making sure you keep your images in one folder on the server (often /images/) and if you have a large number of images consider using sub folders to categorise and store these so you don’t end up with a folder with 12,000 images in it which you can’t manage easily.
Images can be powerful in SEO, so make sure you get the optimisation right and don’t just spam things with the name of the images or use all of your core keywords in the ALT tags.