What Alt Text Is For

Alternative text is the written description attached to an image so that people and machines who cannot see it still understand what it conveys. Screen reader users hear it read aloud. Visitors on failed connections see it in place of the missing image. Search engines use it as one of the strongest available signals about an image's subject, which affects both image search and the topical understanding of the page hosting it. That dual purpose is the key to writing it well. If you write alt text purely for search engines you produce keyword lists that make the page hostile to assistive technology users, and modern search systems are perfectly capable of recognising that pattern. If you write it purely for accessibility you naturally end up with descriptive, specific language that also performs well in search. Accessibility first is both the ethical and the effective approach.

How AAMAX.CO Improves Image and On-Page Optimisation

Image optimisation is one of those details that quietly separates a well-executed site from an average one, and it is part of every on-page engagement we run at AAMAX.CO. We audit entire libraries for missing, duplicated or stuffed alt attributes, write descriptions that serve accessibility and search together, fix file naming and compression, implement responsive image delivery and add the structured data that helps images qualify for rich results. Combined with the rest of our SEO services, that work improves image search visibility, page performance and the experience of every visitor using assistive technology.

The Core Principle: Describe Function, Not Just Appearance

Before writing anything, ask why the image is on the page. An image can be informative, functional, decorative or text-bearing, and each type is handled differently. An informative image conveying content should be described in terms of the information it adds. A functional image, such as a logo inside a link or an icon acting as a button, should describe the destination or action rather than the graphic, because that is what the user needs to know. A purely decorative image adds no information and should carry an empty alt attribute so screen readers skip it silently. An image containing text needs that text available as real text, either in the alt attribute or in nearby page copy.

How Long Should Alt Text Be

Aim for a single clear sentence, usually somewhere between five and about fifteen words, and stop when the essential information is covered. Some assistive technologies truncate very long values, and lengthy descriptions become tiring to listen to when a page contains many images. If an image genuinely requires a long explanation, such as a detailed chart or a complex diagram, keep the alt text short and provide the full explanation in the surrounding copy, a caption or a linked long description. That approach serves everyone better than cramming a paragraph into an attribute.

Practical Writing Rules

Lead with the subject rather than a preamble. Screen readers already announce that the element is an image, so beginning with phrases like image of or picture of wastes the listener's time. Be specific: a golden retriever puppy sitting on a wooden porch is far more useful than dog. Include the detail that matters for the context, which changes with the page; on a veterinary article the breed and posture might matter, while on a product page the colour and material matter most. Include your keyword only where it appears naturally as part of an honest description, and never repeat the same alt text across many different images. Use normal sentence capitalisation, and end with a full stop so screen readers pause naturally between elements.

Before and After Examples

Consider a photograph on a bakery page. Weak alt text reads bakery, bread, artisan bakery, best bakery near me, which is keyword stuffing and tells a screen reader user almost nothing. Better alt text reads baker sliding a tray of sourdough loaves into a stone oven. It is descriptive, natural and still contains meaningful terms. For a product image, avoid product image 1 and write blue waterproof hiking boot with red laces, side view instead. For a chart, replace graph with line chart showing organic traffic rising steadily over twelve months, then give the actual figures in the paragraph beside it. For a logo inside a header link, write the company name rather than describing the shapes, because the user needs to know where the link goes.

When to Leave Alt Text Empty

An empty alt attribute is a deliberate, correct choice for decorative images: background textures, divider graphics, abstract shapes and ornamental flourishes that carry no information. Writing decorative image or leaving the attribute off entirely both produce worse outcomes, because a missing attribute may cause a screen reader to announce the file name. Use an explicitly empty value so the element is skipped cleanly. The same applies when an image duplicates adjacent text exactly; describing it again forces the user to hear the same information twice.

Beyond Alt Text: The Rest of Image SEO

Alt text is one part of a larger picture. Give files descriptive lowercase hyphenated names before uploading, because a name like handmade-leather-satchel-brown adds context that a camera-generated string never will. Compress images and serve modern formats so they do not slow the page, and set explicit width and height so the layout does not shift while they load. Use captions where they genuinely help readers, since captions are visible content and are read by everyone. Include important images in your sitemap, and add relevant structured data on product, recipe and article pages so images can appear in richer result formats. Together these details influence performance, accessibility and visibility across search and increasingly across AI-generated answers, which is why brands investing in GEO services pay attention to them too.

Auditing an Existing Library

Most established sites have accumulated problems. Crawl the site and export every image with its alt attribute, then sort the results to find three categories: missing attributes on informative images, identical alt text repeated across many images, and stuffed values packed with keywords. Fix the highest-traffic and highest-value pages first, especially product pages, service pages and popular articles. Then set a standard for your team so new uploads are handled correctly, ideally enforced with a required field in your publishing workflow rather than left to memory.

Final Thoughts

Good alt text is short, specific and honest. Describe what the image contributes, adjust for whether it is informative, functional or decorative, keep it natural, and never sacrifice clarity for keywords. Do that consistently and you improve accessibility, image search visibility and the overall topical strength of your pages at the same time. If you want your entire image library audited and optimised properly, hire AAMAX.CO and we will handle it alongside the rest of your on-page work.