Why “Alt Text” Is One of the Most Underrated SEO Moves You’re Not Making

I spent three years optimizing my websites for search. I obsessed over title tags, wrote thousands of words of long-form content, built backlinks, improved Core Web Vitals scores. I did the work.

And then someone pointed out that I had barely any alt text on any of my images. Not a few missing. Basically none.

I’d treated alt text like a footnote. Something you technically do. Something accessibility auditors mention. Not something with real impact on search visibility.I was wrong.

What Alt Text Actually Does (That Most Guides Don’t Explain Well)

Alt text — the text attribute on an HTML image tag — does two things. First, it describes the image to screen readers so that visually impaired users can understand what they’re looking at. Second, it gives search engines a text signal for image content that they otherwise couldn’t read.

Search engines are not blind in the way a person can be blind. They can analyze images using computer vision. But their understanding is still probabilistic and imperfect. Alt text acts as a direct, high-confidence signal: this is what this image contains. That signal matters.More specifically, alt text feeds into two distinct ranking systems: the standard web ranking and Google Image search ranking. Images can drive meaningful referral traffic. A recipe blog with properly optimized images might get 30% of its organic traffic from Google Images. A travel blog might see even more.And yet most sites treat their images as decoration.The Quality Problem Nobody Talks About

Here’s the thing people don’t say: bad alt text is almost as useless as no alt text.

Generic descriptions — “image of a woman smiling” — add minimal signal. Keyword-stuffed alt text — “best WordPress SEO plugin buy cheap WordPress SEO plugin” — can actually hurt you.

Good alt text is specific, descriptive, and contextual. It describes what’s actually in the image, in plain language, with natural inclusion of relevant keywords where they genuinely fit.

“A developer looking at code on a laptop next to a coffee cup” is good alt text for a generic blog header. “A developer debugging a React component in VS Code” is better, because it’s specific and contains real keywords that people search for.

The difference compounds across thousands of images.How to Actually Check Your Alt Text Quality

Checking whether your alt text is present is easy — any number of browser extensions or SEO tools will show you which images are missing alt text at a glance.

Checking whether your alt text is good is harder. You need to actually read the descriptions and ask: does this describe what a sighted person would see? Does it include context a screen reader user would need to understand the content? Are relevant keywords present naturally?

This is where most site owners stop — at the binary question of “present or absent” — when the real value is in the quality dimension.

There are now tools that can audit alt text quality, not just presence. They’ll flag descriptions that are too short, too generic, suspiciously similar across images, or stuffed with keywords. I’ve found them enormously useful for identifying where I was technically “compliant” but actually underperforming.

The Alt Text and Accessibility Connection

Here’s something I’ve come to believe: the sites with the best alt text tend to be sites that approach it from an accessibility mindset rather than a pure SEO mindset.

When you’re writing alt text for a screen reader user, you’re forced to be specific and accurate. You can’t be vague, because a vague description is useless to someone who genuinely cannot see the image. That specificity and accuracy is exactly what search engines reward.

It’s the same phenomenon you see with content that performs well for voice search — natural language, direct answers, specific details. Writing for humans produces content that algorithms like.

he Practical Step

If you haven’t done an alt text audit on your site, that’s the place to start. Not a quick scan — a real audit that looks at quality, not just presence.

I put together a free tool at altaudit.com/free-alt-text-checker that does exactly this. You enter your URL, and it checks both whether alt text exists and gives you a quality assessment of what’s there. It takes about 90 seconds and will show you more about your image optimization than most full SEO audits do.

If you’ve been putting off alt text as a “someday” project, this is your nudge to treat it as a priority. The combination of SEO value and accessibility impact makes it one of the higher-ROI things you can do on a site that’s already live.