Effective alt text serves two purposes: it makes images accessible to people using screen readers, and it helps search engines understand your visual content. These guidelines apply whether you’re writing alt text manually or reviewing AI-generated output.Documentation Index
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Writing alt text
Be informative, not exhaustive
Focus on the information that matters. Good alt text conveys what the image communicates — not every visual detail. Do: A woman holding a reusable coffee cup in a park Avoid: A smiling young woman with long brown hair wearing a green jacket holding a white reusable coffee cup while standing near trees in a sunny parkSkip “image of” and “photo of”
Screen readers already announce that an element is an image. Prefixes like “image of” or “photo of” add length without value.Keep language accessible
Straightforward vocabulary and simple sentence structure work for everyone, including screen reader users. Avoid jargon unless it’s meaningful to your audience.Match the context
Alt text should reflect why the image is on the page. The same photo needs different alt text depending on where it appears.- Product pages — include product type, color, key attributes, and angle/positioning. Example: Ergonomic office chair in black mesh, angled three-quarter view
- Editorial content — convey the emotional or thematic significance of the image rather than a literal description
- Data visualizations — describe the trend or conclusion, not just the visual structure. Example: Bar chart showing 40% revenue growth from Q1 to Q4 2024
SEO and AEO considerations
Well-written alt text improves both traditional search rankings and visibility in AI-generated answers (Google AI Overviews, Perplexity, ChatGPT with browsing). The same principles apply to both.Use keywords naturally
Keywords that appear naturally in a description improve discoverability. Forced keyword insertion degrades readability and provides no benefit. Do: Ergonomic office chair with lumbar support in black mesh Avoid: Office chair ergonomic lumbar support buy black mesh chair SEOWrite for meaning, not just metadata
Answer engines reward alt text that captures the actual significance of an image. An image illustrating a concept should have alt text that names the concept, using terminology consistent with the surrounding page content. Do: Diagram showing the three-stage customer onboarding flow: sign-up, verification, first session Avoid: Diagram with arrows and boxesGoogle recommends writing alt text for users first, not search engines. See Google’s image SEO best practices for more.