Citation half-life
Citation half-life describes how quickly unchanged content loses visibility in AI answers. A large 2026 study measured that, on average, content is cited less often after roughly 4.5 weeks — making freshness a measurable lever for AI visibility.
The term transfers half-life from physics to AI answers: how long until an unchanged piece of content is cited only half as often? A study by Scrunch and Stacker (2026) analysed more than three million citation events across eight industries over 26 weeks — finding a median half-life of roughly 4.5 weeks, ranging from about 3.4 weeks (ChatGPT) to almost 6 weeks (Perplexity) depending on the AI system.
The reason: AI systems visibly prefer fresh sources. Older content is not wrong — newer content simply crowds it out. According to the same analysis, sites that update regularly are cited about three times as often (3.2×) as sites left unchanged.
For businesses this suggests a simple rhythm: review and visibly maintain core facts such as opening hours, services and prices on a regular basis. AI visibility is not a one-off task but ongoing care — and citation half-life makes that measurable for the first time.
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Frequently asked questions.
Is it enough to make my website AI-ready once, or do I need to keep maintaining it?
No — AI visibility is not a one-off task, it requires ongoing upkeep. A large study on AI citations found that unchanged content gets cited less often after roughly 4.5 weeks, because AI systems favour sources that are visibly kept current.
In practice, that means opening hours, services and other core facts should be checked regularly and updated immediately when they change — the fresher the content, the more likely it is to show up in AI answers.
What does GEO get me — why should my website be cited by AI?
When more and more people get their answers straight from ChatGPT, Perplexity or Google's AI, whether you get found is no longer decided by your Google ranking alone — but by whether the AI names you as a source. That is exactly what GEO (Generative Engine Optimization) does: it prepares your content so AI systems read it correctly, understand it and cite it in their answers. The benefit is concrete: you get recommended when a potential customer asks the AI for a provider like you — with clear, independently readable statements, structured data and machine-readable formats. If you're not visible here, you simply don't exist for this growing group of searchers.