An HTTP referrer header indicating that a user clicked to your site from an AI engine like ChatGPT, Perplexity, Gemini, or Claude.
An AI referrer is the source/medium signal in your web analytics indicating an AI engine drove the visit. Common AI referrer domains include chatgpt.com, perplexity.ai, gemini.google.com, claude.ai, and copilot.microsoft.com. Capturing AI referrers cleanly is harder than traditional referrers because (a) some AI engines strip referrer headers, (b) users often access AI engines through embedded interfaces that don't pass referrers, and (c) GA4's default channel grouping classifies many AI sessions as 'direct' or 'unassigned.'
AI referrer data is the foundation of session-level AEO attribution. Without clean AI referrer capture, you can't tell which traffic came from AI engines, let alone which AI citations drove which sessions.
A user reads a Perplexity answer that cites your brand and clicks through. In GA4, that visit might appear as 'perplexity.ai / referral' (good) or as 'direct' (common, bad). Setting up AI Search as a custom channel group with explicit source matches catches the cleanly-attributed sessions.
The terms in this glossary aren't theoretical — they're what Lantern's product calculates and reports every month for B2B SaaS teams. See yours in 7 days. 14-day free trial.
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