Grounding is a language model basing its answer on sources retrieved by live web search. Without grounding, the answer comes from training memory and is closed to recent changes.
The distinction is decisive for measurement. A content change you make today can only affect grounded answers; counting a memory-based mention as "earned visibility" is misleading.
Platforms differ here: Perplexity and ChatGPT search mode almost always use live sources, while pure chat modes often answer from memory. If your measurement tool does not report the two separately, it is collapsing two different things into one number.
Why grounding is the foundation of GEO
A language model can answer from two different places: what it learned during training (memory) or the live search results it retrieves in the moment (grounding). For GEO the difference decides everything.
Answers from memory are stale and nearly impossible to change — not until the model is retrained. Answers produced with grounding can include a page you published yesterday. The area GEO work can actually influence is the second one.
How can you tell which kind you got?
The most reliable signal is citation: if the answer carries links, live search was used. With no links, the answer most likely came from memory.
A second signal is recency: if the model describes an event after its training cutoff correctly, retrieval is in play. Recording this distinction matters during measurement — you cannot change a mention that comes from memory through content work, but you can change what is missing from grounded answers.
Frequently asked
Can I correct wrong information in a model's memory?
Not directly. Memory changes with retraining. What you can do is make the correct information dominant and easy to find in live search, so that grounded answers surface it.
Does every answer use live search?
No. Engines decide based on question type; retrieval kicks in for questions needing recency or disambiguation, and often does not for general definition questions.
With grounding, how fast does new content take effect?
It depends on crawling and indexing speed. Submitting via IndexNow shortens that on the Bing side — no guarantee, but a measurable difference.
