What Alt Text Does and Why Google Cares

The alt attribute is a short written description attached to an image in HTML. Its original purpose was accessibility: screen reader users hear the alt text in place of the picture, and it also displays when an image fails to load. Google relies on the same attribute because a crawler cannot see an image the way a person does. Alt text, the surrounding copy, the file name and the page context together tell Google what an image depicts, which determines whether it appears in image search and whether it reinforces the topic of the page. With visual search growing and image results appearing inside standard listings, alt text has become a practical traffic channel rather than a compliance checkbox.

How AAMAX.CO Can Help With Image SEO

AAMAX.CO is a full service digital marketing company offering web development, digital marketing and search optimisation worldwide, and image optimisation is part of every technical audit we deliver. We identify missing and duplicated alt attributes at scale, rewrite them for both accessibility and relevance, compress and convert assets to modern formats, implement responsive image markup, and add image sitemaps and structured data where they earn extra visibility. If your site has hundreds of untagged images, our SEO services can fix the backlog and put a process in place so it never builds up again.

Writing Alt Text That Works for People First

The best alt text describes the image accurately and concisely to someone who cannot see it. Aim for roughly five to fifteen words, describe the subject and the meaningful detail, and skip phrases like image of or picture of because assistive technology already announces that it is an image. If the picture contains text that matters, include that text in the description. If the image conveys an action or result, describe the action rather than listing objects. A useful test is to read the alt text aloud with the surrounding paragraph and check whether the page still makes sense.

Adding Keywords Without Crossing the Line

Alt text is a legitimate place for a relevant keyword, but only when the keyword genuinely describes the image. If a photograph shows a technician installing a solar panel on a tiled roof, including the service phrase is natural and helpful. Stuffing a list of unrelated terms is a spam signal and actively harms the experience of screen reader users. Never repeat the same alt text across dozens of images either, because duplication tells Google the images add no unique value. One primary descriptive phrase per image is the right target.

Handling Decorative and Functional Images

Not every image needs a description. Purely decorative elements such as background flourishes, spacer graphics and repeated dividers should carry an empty alt attribute so screen readers skip them silently. Omitting the attribute entirely is different and worse, because some readers then announce the file name. Functional images require a different approach: if an image is also a link or a button, the alt text should describe the destination or the action, not the picture. A logo that links to the homepage should therefore describe the brand rather than the graphic design.

File Names, Captions and Surrounding Context

Alt text is one part of a wider set of signals. Rename files before uploading so the name is descriptive, lowercase and hyphenated instead of a camera code. Add captions where they help the reader, since captions are visible content that Google reads and users often scan. Place images near the paragraph they illustrate so the surrounding text reinforces the subject. Include a title attribute only when it adds genuine value, because it appears as a tooltip and is not a substitute for alt text.

Technical Choices That Multiply the Benefit

Well-described images still hurt you if they load slowly. Serve modern formats such as WebP or AVIF, compress files before upload, and size them appropriately rather than relying on the browser to scale a large original. Use responsive srcset and sizes attributes so mobile devices download smaller variants. Set explicit width and height to avoid layout shift, and lazy load images below the fold while eagerly loading your hero image so the largest contentful paint stays fast. These choices protect Core Web Vitals, which influence both rankings and conversion.

Image Sitemaps and Structured Data

Help Google discover your visuals by including images in your XML sitemap, particularly when they are loaded through scripts or galleries. Add structured data where it applies: product schema with image fields for ecommerce, recipe or how-to schema where the images illustrate steps, and article schema for editorial content. Machine-readable descriptions help search engines and AI answer systems associate your visuals with the right entity, which is a core part of our GEO services.

Common Mistakes to Avoid

The most frequent errors are simple. Leaving alt text blank on meaningful content images loses both accessibility and search value. Auto-filling alt text with the file name produces unreadable strings of hyphens and numbers. Copying the page title into every image alt attribute creates mass duplication. Writing paragraph-length descriptions overwhelms screen reader users. And relying on text baked into an image for important information means neither Google nor assistive technology can read it, so put critical copy in real HTML instead.

Auditing an Existing Site

To fix a site at scale, crawl it with an SEO auditing tool and export every image with its alt attribute. Sort by missing, duplicated and overly long values, then prioritise images on your highest-traffic and highest-value pages. Content management systems usually let you edit alt text in the media library, and bulk editing plugins can speed up the work. Re-crawl afterwards to confirm the fixes are live, and watch the image search section of Search Console for impression growth over the following weeks.

Turning Image Optimisation Into Traffic

Alt text is a small field with outsized returns: it makes your site usable for more people, clarifies your content for search engines, and opens a traffic channel most competitors ignore. Combine it with fast, well-named, properly marked-up assets and it strengthens the ranking of every page it appears on, especially when it runs alongside a coordinated digital marketing effort. If you want the audit and the implementation handled for you, hire AAMAX.CO for SEO services and we will make every image on your site work harder.