Missing Alt Text Is an SEO and Accessibility Problem

Alt text is unusual among on-page fixes because it genuinely matters for two audiences that don't often overlap in most SEO advice: search engine crawlers, which can't "see" an image and rely on alt text to understand it, and screen reader users, who hear the alt text read aloud in place of the image itself.

What good alt text actually looks like

The most common mistake isn't a missing alt attribute — it's a lazy one. "image1.jpg," "photo," or the file name copied verbatim tells a screen reader user nothing and gives a search engine nothing to index. On the other end, alt text stuffed with keywords ("best plumber Chicago affordable plumber near me") reads as spam to both audiences and actually hurts more than an empty attribute would.

A useful test: describe the image the way you'd describe it over the phone to someone who needs to know what's there and why it matters on this page. For a product photo, that's the product and its distinguishing detail. For a decorative image that adds nothing informational, the correct alt text is an empty string (alt="") — not a missing attribute, an explicitly empty one, which tells assistive tech to skip it entirely rather than guess.

Decorative vs. informational is the fork in the road

This is where most sites go wrong in one of two directions:

• Every image gets alt text, including the decorative divider graphics and background textures that add nothing to the content — which just adds noise to a screen reader's pass through the page
• Every image gets left blank, including product photos, charts, and screenshots that carry real information the surrounding text doesn't repeat

The pages this affects most

Product listings, blog posts with screenshots or diagrams, and any page that leans on images to convey information a caption doesn't fully restate. If a chart shows a trend and the alt text just says "chart," anyone not looking at the image — a screen reader user, or a search crawler evaluating the page — gets nothing from it that the surrounding paragraph didn't already say.