Alt Text

Alt text is the alt attribute inside an <img> tag. I used to treat it as a free keyword slot. That was a mistake. It exists first to describe an image for someone who cannot see it — a screen-reader user, a browser with images turned off, a slow connection where the image fails to load. Search engines read it for context, but that is a side benefit, not the purpose. The order matters: describe what you see, not what you want to rank for. A product image of a blue raincoat should say "blue waterproof raincoat on a hanger", not "raincoat buy now best price".

Keep it under 125 characters and avoid repeating the page title. If the image is decorative — a border line, a background pattern — use an empty alt attribute (alt="") so screen readers skip it. If the image is a link, the alt text should describe the destination, not the image. That is a rule I ignored for years.

I now write alt text by covering the image on my screen and asking myself: "What would I say if someone asked me what is here?". The answer, stripped of fluff, is the alt text. That approach works for accessibility and passes whatever SEO check Google runs. I have seen pages where better alt text correlates with a small bump in image search impressions, but that is a side effect. The real win is that a visitor using a screen reader gets the same information as a sighted one.

Alt text matters most on pages where the image carries information the surrounding text does not repeat. [E-commerce product pages](/on-page-seo/) are the clearest case: each product image shows colour, texture, angle details a shopper needs. If I skip alt text on those, I lose image-search traffic and, more importantly, make the site unusable for blind visitors.

Infographics and data visualisations are another high-stakes scenario. A chart about market share has no meaning if the alt text says "bar chart". It should say "bar chart showing 40% of the market belongs to brand A, 30% to brand B". That is tedious to write, but it makes the content accessible. For complex graphics, I link to a text table nearby and make that the longdesc equivalent.

Navigation icons — the hamburger menu, the search magnifying glass — need alt text that describes the action: "open menu", "search site". Not "icon". I have seen sites where every navigation image has the same alt text: "image". That is noise for screen readers.

From an SEO perspective, Google Images is a real traffic channel. I worked on a travel site where optimising alt text on 300 destination photos brought image-search traffic from 0 to 12% of total organic in six months. But I only saw that after I stopped stuffing keywords and started describing the photo. The [Image SEO](/image-seo/) fundamentals matter: descriptive filenames, captions, and yes, alt text.

Finally, if you work on a site that must meet WCAG 2.1 AA — government, education, large enterprise — missing alt text is a compliance failure. I use the W3C WAI tutorial as my standard. Checking alt text is now a step in my [content audit](/content-audit/) checklist.

My first alt text mistake was treating it as a one-off SEO task. I wrote alt text once when an image was uploaded and never revisited it. But sites change: an image is replaced, a product is updated, a blog post gets a refresh. I now run a monthly HTML report that flags images with missing or generic alt text. The last audit on a client site found 200 images without alt text out of 500. Fixing them improved image search impressions by 18% over three months — and one screen-reader user emailed to thank us. That email mattered more than the traffic.

Second mistake: copying competitors' alt text. I assumed if a rival used "SEO content writing services" on every image, that was best practice. It is not. Every image has a unique context. A photo of a laptop on a homepage says "laptop on a wooden desk", not "buy laptop now". I now write alt text per image per page, even if the same image appears elsewhere. The context changes the description.

Third mistake: thinking every image needs alt text. Decorative images — spacers, borders, purely visual flourishes — should have an empty alt="". Giving them alt text forces screen readers to announce content that has no function. I wasted hours writing alt text for background patterns before I understood this.

Fourth mistake: measuring the wrong thing. I used to check rankings for image queries. That is noisy. I now measure screen-reader compatibility and accessibility score from tools like WAVE. Those numbers tell me if my alt text actually works. The [SEO content strategy](/seo-content-strategy/) should always start with the user, and alt text is a perfect example of that principle.