ALT tags are important for enhancing user experience and allowing search engines to easily crawl your content. Learn how to identify missing ALT tags, fix them effectively and take a proactive approach to leverage image SEO for organic traffic growth.
Shane Parkins has spent over 14 years helping businesses optimise their websites for better search rankings and accessibility. One of the simplest yet most overlooked SEO elements is image ALT tags. These tags help search engines understand what an image represents, improving indexing, accessibility, and user experience.
In this guide, Shane explains why ALT tags matter, how they impact SEO, and best practices for writing effective descriptions. Optimising your images properly ensures better search visibility, improved rankings, and a more accessible website for all users.
Images have the potential to not only complement the visual experience of a site but it can also heavily underpin some elements of your SEO strategy. The ALT tag is a key feature to driving performance when it comes to images; it’s unfortunately a key area that is often overlooked by webmasters and site owners.What I see time and time again is a website being built, I’ll do an assessment and it’ll likely flare up huge warnings around ALT tags, perhaps WebP or even image sizes. The key issue this surfaces is that webmasters need to retrospectively go back; getting this nailed down at the point of publishing content will make life so much easier for everyone. It’s also important to remember that this just isn’t an SEO feature, it serves a significant purpose for users who perhaps can’t see images. For visually impaired users who rely on text readers to browse a website, ALT tags can be read to a visitor to describe the content. As you are considering your image use and ALT tags, I’d also encourage you to group images near content that it’s relevant to, ensure the image name is a good reflection and also use the latest technology such as WebP – finally, try and make the image relevant to the content too.
Every SEO tool worth its salt will be able to identify this for public-facing images. Screaming Frog, SEMRush, ahrefs and SiteBulb will scan your site and look for this specific ALT tag nearby to images. It’s not often required for decorative images but certainly for images embedded into the content. If you’re like any of the websites I deal with, there is a good possibility there will be a significant list of images used on the site but doesn’t have a suitable or correct ALT tag usage.
A common mistake I see when handling image ALT tags is fixing it on a page by page basis, instead, try and assign an ALT tag within the database attached to the media, which means this ALT tag will be used every time it is used. The description used at this level should serve you well because the nature of the image will not change regardless of where it is used. If you feel the need to change the ALT description on a page by page basis, be careful you are not trying to manipulate the tag for just SEO purposes. I’m a massive fan of WordPress, for example in this particular CMS, you can do this via the Media section and this should populate the front end across the site – other CMS’ will vary.
You need to apply a descriptive ALT tag, if it’s an apple then name it “Red apple on a table”, imagine you are describing the image to someone who cannot see it. Generic descriptions are fine but try to be a little specific, not too excessive, around 5-6 words are typically fine. Don’t try and stuff keywords in here for the sake of it but be really descriptive on what it is.
Add the ALT tag within the HTML, also you don’t need to do this for every image on your site, if it’s a decorative image then I’d leave this out for now. Only apply images with ALT tags to main content pieces.
Music to my ears this, because if you take a proactive approach to ALT tags, presuming you aren’t handling a massive eCommerce store with over 500,000 images, get ahead and add these in at the point of publishing content. Take that extra 5 minutes to write descriptive ALT tags on that blog post, buyers guide or product breakdown. Over time it’ll really serve you well as image SEO can also help drive organic traffic for keywords which are very difficult to rank for.
I’d always recommend frequent SEO crawls of your site, if new images are used they can sometimes be published without an ALT tag.
Don’t presume no errors are good news, if your site is really old you may have ALT tags on all images but may be adhering to really bad advice of keyword stuffing. Spot check a few older pages to see if you agree with the ALT description. If you are feeling really techy and are using a database to power the site, head on over to the media table and scan through the ALT tags and look for excessive and spammy ALT tags.
Don’t forget to use a relevant name for the image, 1.jpg with no ALT tag doesn’t help anyone from accessibility or SEO perspectives albeit the technology available now to identify what is in images is probably more accurate than your ALT tag. Nevertheless, I’d still apply this tag wherever possible.
No matter how tempting, don’t put the keywords you want to rank for in here, create a descriptive ALT tag and if it has keywords in there, great, if not – no problem.
Robust ALT tags, the latest technology for images (webp), minimum use when necessary and suitably sized images will always serve you well over time – it certainly pays dividends to get ahead of this – websites can accumulate issues very rapidly around these types of errors and ultimately miss out on big opportunities.
Always remember if you are changing the image name in FTP, you may cause some issues with broken images – proceed with caution and with the developer’s blessing.
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