Descriptive Image Alt Text

Descriptive alt text is now a multi-purpose signal. Its original purpose — accessibility for screen-reader users — remains its primary justification. But the secondary purposes have expanded substantially: SEO crawlers use alt text to understand image relevance, classical search uses it for image search results, and multimodal AI engines now combine alt text with their own image parsing to construct multimodal answers. A chart that has 'chart showing 62% of B2B AEO practitioners measure citation rate manually, source: Storyzee 2026 research' as alt text is far more useful across all four purposes than the same chart with 'chart.png' or 'AEO citation rate'.

The practice is straightforward but often neglected. Write alt text as a complete short sentence that describes what is in the image and why it matters in the context of the surrounding content. For data visualizations and infographics, the alt text should communicate the key data point or finding — what the image shows, not just what it is. For decorative images (genuine ornamentation), use empty alt text (alt="") rather than keyword-stuffing meaningless descriptions. For complex images, the alt text can summarize while a longer description nearby provides full detail.

For AEO specifically, alt text gains importance as multimodal AI engines become more common. Engines like Gemini and increasingly ChatGPT can process images directly but combine that processing with the surrounding alt text, captions, and contextual prose to construct their understanding. Brands that treat alt text as a serious content asset — rather than a perfunctory SEO tax — benefit when those multimodal engines surface their visualizations in answer responses. The work is small per image but compounds across a content library as multimodal AI capabilities continue to grow.