---
title: "Alt text"
description: "A short description attached to an image so people and systems that cannot see it still get the meaning."
category: "Editorial craft"
canonical: "https://contentlexicon.com/alt-text"
updated: "2026-10-11"
---

# Alt text

_Editorial craft_

> A short description attached to an image so people and systems that cannot see it still get the meaning.

Alt text is short for alternative text. Screen readers use it for people who are blind or partially sighted, browsers can show it when an image fails to load, and search engines and AI systems use it to understand what an image is for. Good alt text describes the meaning of the image in context rather than listing visible objects.

Ask what the reader would miss if the image disappeared. That's usually what the alt text needs to cover. Decorative images should be marked as decorative so they're skipped rather than described.

## Why it matters for content

Alt text makes image-based meaning available in words. That matters first for [accessibility](https://contentlexicon.com/accessibility), but it also improves the quality of search, indexing and machine use of content. A chart, infographic or screenshot may carry key information; if that information exists only in pixels, many readers and systems will miss it entirely. Writing alt text forces a team to decide what an image is doing on the page.

Images that carry information need it most: charts, diagrams, product screenshots, photographs used as evidence, event images with visible text and graphics that summarise a point. It's especially important on high-traffic pages, campaign pages and service pages where missing visual information changes what a reader can understand or do.

## How AI changes the picture

Search engines, image systems and generative tools all need text if they're to do anything sensible with an image. Alt text is written for people and should stay that way, but a missing description now costs you with machines as well.

AI can also write the alt text. Automatic image description is useful for a first draft, or for making a start on a media library with thousands of undescribed images. But a model describes what's visible, not why the image is there. It can see a bar chart with five blue bars; it can't know that the point of the chart is the drop in the final year. Someone who knows the page still has to decide what the image is for.

## Questions people ask

**Do all images need alt text?**

All images need a decision. Informative and functional images need alt text. Decorative images should usually have empty alt text (alt="") so screen readers skip them.

**Is alt text the same as an image caption?**

No. A caption is visible to everyone. Alt text is primarily for people and systems that can't access the image visually.

**Should alt text describe every detail?**

Usually not. It should describe what matters in context. A portrait, a chart and a navigation icon all need different levels of description.

**Does alt text help SEO?**

Sometimes, indirectly, because it helps systems understand an image. But writing it for search rather than for meaning usually produces bad alt text.

## Learn more

- [Alt Text as Poetry](https://alt-text-as-poetry.net/) – Bojana Coklyat and Shannon Finnegan's workbook reframes alt text as a creative practice, with writing exercises built around voice and belonging rather than compliance. A deliberately different register from the standards links.
- [An alt Decision Tree](https://www.w3.org/WAI/tutorials/images/decision-tree/) – W3C's flowchart for deciding whether an image needs alt text and what kind.
- [WebAIM: Alternative Text](https://webaim.org/techniques/alttext/) – a detailed explainer of what good alt text does.

Related terms: [Accessibility](https://contentlexicon.com/accessibility), [Automated testing](https://contentlexicon.com/automated-testing), [Metadata](https://contentlexicon.com/metadata), [WCAG](https://contentlexicon.com/wcag)

Also called: Alternative text

This page was last reviewed in October 2026.