Best alternative text practice for SEO compared, and the four cases where alt text is not the fix

Alt text has one job that genuinely matters and one that gets overstated every time the subject comes up. Separating them stops people spending a week on the wrong one.

The two jobs, in order of how much they matter

The job that is not negotiable is accessibility. Alt text is what a screen reader says in place of an image. If the image carries information, the alt text has to carry the same information, and if it does not, a person using a screen reader loses part of your page. That is the reason the attribute exists and it is reason enough on its own.

The job that is overstated is ranking. Alt text is a genuine signal. It is how an image gets understood for image search and it adds a small amount of context to the page it sits on. It is not a lever that moves a page's position on a competitive query, and treating it as one is how people end up with three hundred perfectly described images and the same position they started with.

The honest summary. Write alt text because leaving it out breaks your page for some of your readers. Expect a modest search benefit, concentrated in image search, and do not budget for more than that.

How to write it, in four rules

One, describe the function, not the file. Ask what a reader would lose if the image vanished, then write that. A product photo's function is usually to show a specific variant, so name the variant.

Two, leave decorative images empty, deliberately. An empty alt attribute is the correct markup for an image that carries no information, and it is better than a description, because it tells the screen reader to skip rather than to read out something pointless. Missing and empty are different things. Empty is a decision.

Three, do not write the words "image of". The screen reader already announced it as an image. Starting the text with those words makes every image read worse.

Four, stop before it becomes a sentence of keywords. A short accurate description is correct. A description stuffed with query terms is both worse for a screen reader and the single most recognisable low quality signal in this part of a site.

The four cases where alt text is not the fix

One, when the image is text. If your price list, specification table or headline is baked into a picture, no alt text recovers that content properly. Put the text on the page as text and keep the image as illustration.

Two, when the image is not being loaded. If images sit behind lazy loading that never resolves without a scroll event, or behind a script, the alt attribute is not the problem. Nothing is reaching a crawler or a reader at all.

Three, when the real problem is weight. A page carrying several megabytes of images has a speed problem, and a speed problem affects every query the page has. Perfect alt text on a slow page is a well labelled slow page. Compression and correct sizing come first. Some platforms do a lot of this for you, which is worth checking before you buy a tool for it.

Four, when the page has no reason to rank. If the page is thin, duplicated or answers nothing a person searched for, alt text is a detail on a page with a bigger problem.

What your platform already controls

Before buying anything, check what you already have. We read Wix's SEO page at wix.com/seo on 21 October 2026 and it states that you can "Customize your site's meta tags, URL structure, canonical tags, structured data markup, robots.txt file and more", that "Wix adds structured data markups to dynamic pages like products, events, blog posts, and more", that "All Wix sites automatically come with their own editable robots.txt file", and that images are "instantly compressed, resized, and converted to WebP for accelerated page loading". That last clause matters for case three above. If your platform already converts and resizes, image weight may not be your problem.

We also tried to read the equivalent Squarespace page the same day and squarespace.com/seo returned HTTP 404. We are reporting that rather than quoting an older version from memory. A product page can move or be renamed under you, and a 404 today is a reason to check the current page rather than a reason to conclude anything about the product.

Where we sit, and it is not inside this category

We do not sell an alt text tool and we are not going to pretend that image markup is our category. AI Knows Us measures one thing, which is whether ChatGPT, Gemini, Perplexity, Claude and Google AI Overviews name a business when a buyer asks who to buy from.

The connection to this page is real and narrow, so here it is stated narrowly. On page work like alt text is how a search engine understands what your page is about. That understanding is upstream of whether an assistant can describe you accurately at all, which is why on page hygiene is worth doing. But it is measured completely differently. On page SEO is measured by positions and impressions. The naming layer is measured by asking a buying question and counting whose name comes back, and there is no position number in that answer because there is no results page. Our published entry for that measurement is Growth at $299 a month, with 100 buyer questions and all five engines, per aiknowsus.com/llms.txt read 21 October 2026. The cheaper SEO Start at $149 publishes 0 questions, 0 credits and 0 engines and does not do this job.

What to read next

For worked alt text lines across fourteen kinds of image, including the cases where an empty attribute is correct, see alt text examples, worked lines for fourteen kinds of image. For what the automated tools actually produce and how to review their output, see alt text generator, what the tools actually produce.

If your images are the point of your business rather than decoration on it, the combination of image weight, image markup and local search is a specific problem and we worked it through for one trade at SEO for wedding photographers, venue pages, real wedding posts and image speed. We link to that deliberately. When we measured inbound links across 2,286 stored page bodies on 21 October 2026, no other page on this site links to that one, and 939 of our 2,200 live pages were in the same position, 42.7 percent, an upper bound.