What is Alt Text? Why It Matters for SEO and Accessibility (2026)

What is Alt Text?

Alt text is the value of the alt attribute on an HTML <img> element. It is a text alternative that describes the image's content and function for users and machines that cannot see the image. It does three jobs: screen readers announce it to visually impaired users; search engines read it to index the image and connect it to relevant queries; and browsers display it as fallback text if the image file fails to load.

The alt attribute is required on every <img> element by the HTML specification. The value can be a descriptive string for informative images, or an empty string (alt="") for purely decorative images that should be skipped by screen readers. What is never acceptable is omitting the attribute entirely.

Why Alt Text Matters for Accessibility

Roughly 2.2 billion people worldwide live with some form of vision impairment. Many use screen readers to navigate the web. When a screen reader encounters an <img> element, it reads the alt text aloud. Without alt text, the user either hears the image file name (which often looks like "IMG_4382.jpg") or nothing at all.

WCAG 2.1 Success Criterion 1.1.1 requires that all non-text content have a text alternative that serves an equivalent purpose. This is a Level A requirement, the most basic level of accessibility compliance.

Legal compliance

• United States: The ADA has been interpreted by courts to apply to commercial websites. WCAG 2.1 Level AA is the de facto compliance standard.

• European Union: The European Accessibility Act, in force since June 2025, requires most consumer-facing digital services to meet WCAG 2.1 Level AA.

• United Kingdom: The Equality Act 2010 requires reasonable accessibility accommodations on UK websites.

Missing alt text is one of the most commonly cited issues in accessibility lawsuits because it is easy to detect with automated tools and undeniably violates WCAG 1.1.1.

Why Alt Text Matters for SEO

Alt text is one of the highest-leverage on-page SEO improvements you can make. Search engines cannot "see" images the way humans do. The alt text remains the most reliable signal Google uses to understand what an image depicts and how it relates to the surrounding page content.

Google Image Search ranking

Google Image Search drives substantial referral traffic for many sites. Pages with descriptive, accurate alt text rank better in Google Image results for related queries. A product page with alt text "blue running shoes for women size 8" can appear in image searches for that exact query.

Topical relevance for the parent page

Google reads alt text as part of the page's overall content. Images with alt text mentioning the page's topic reinforce topical relevance and can help the page rank better for text-based queries, not just image queries.

Documented as a Google ranking signal

Google has publicly stated in its Search Central documentation that descriptive alt text helps Google understand image subject matter. Unlike many SEO claims, this is officially confirmed rather than inferred.

How to Write Good Alt Text

Be specific and descriptive

Describe what the image actually shows in enough detail that someone who cannot see the image gets the same information as someone who can. "Dog" is too vague. "Golden retriever puppy sitting in a field of yellow dandelions" is specific.

Include keywords naturally

If the image relates to a keyword you want the page to rank for, include that keyword in the alt text naturally. Do not stuff multiple keywords or write alt text that reads like a keyword list. Keyword stuffing in alt text can trigger algorithmic penalties.

Keep it under 125 characters

Most screen readers cut off alt text at around 125 characters. Aim for one descriptive sentence. If an image needs more explanation, the additional information belongs in a caption or body text, not in the alt attribute.

Do not start with "image of" or "picture of"

Screen readers already announce the element as an image before reading the alt text. Starting with "image of" is redundant and wastes characters.

Consider context

The same image can warrant different alt text on different pages. A coffee cup photo on a cafe homepage might get "espresso in a white ceramic cup on a wooden cafe table." The same photo on a product page might get "white ceramic espresso cup, 6 ounce capacity, dishwasher safe."

Decorative images get empty alt

Background patterns, dividers, decorative icons, and any image that adds no informational value should use alt="". This explicitly tells screen readers to skip the image.

Examples of Good vs Bad Alt Text

Decorative Images and Empty Alt

Not every image on a page is informative. Background patterns, dividers, and decorative icons that add no informational value should use alt="". This explicitly tells screen readers to skip the image. Adding meaningless alt text like "decoration" or "background" creates noise for screen reader users without providing any benefit.

Alt Text vs Title Attribute vs Filename

How to Audit Alt Text on a Site

Google Lighthouse

Lighthouse, built into Chrome DevTools, includes an Accessibility audit that flags every image missing an alt attribute. Open DevTools, click the Lighthouse tab, check Accessibility, and run the audit.

axe DevTools

A free Chrome and Firefox extension that catches missing alt text, empty alt that should be descriptive, and decorative images that should have empty alt but do not. Generally considered the gold standard for in-browser accessibility testing.

WAVE

WAVE by WebAIM provides a visual overlay showing accessibility issues directly on the page. Missing alt text appears as a red icon on the affected image. Available as a Chrome extension and at wave.webaim.org.

Screaming Frog and site crawlers

For full-site audits, a site crawler like Screaming Frog scans every page, lists every image, and reports the alt attribute (or its absence) for each one. Filter by "missing alt text" to find specific problems quickly.

If You Have a Framer Site

Framer provides an Alt Text field on every image component placed on the canvas. Select the image element, open the right-side properties panel, scroll to the Accessibility section, and type your alt text. For decorative images, leave the Alt Text field empty and Framer outputs alt="". For CMS images, add an Alt Text field to your CMS collection schema and bind the image component's Alt Text property to that field.

The problem is scale. A typical Framer site has dozens or hundreds of images spread across canvas pages and CMS collections. Manually auditing every image is impractical inside the Framer editor (see our guide on adding alt text to Framer images at scale), which has no list view of all images on the site, no missing-alt warning, and no way to edit alt text in bulk.

RankFrame Image SEO solves the audit problem with a built-in module that scans every image on your Framer site, both Canvas images and CMS images, and reports which ones are missing alt text, which have generic or duplicate alt text, and which have alt text outside the recommended length range. For sites with significant alt text gaps, RankFrame includes AI-powered alt text generation. Click Generate on any image (or run bulk generation across all flagged images), and RankFrame analyzes the image content and the surrounding page context to draft descriptive, SEO-friendly alt text for each one.