Source Grounded AI: How NotebookLM Reduces Hallucinations | NotebookLM

Upload Sources

PDFs, websites, YouTube, audio, Google Docs, Slides

Indexing

Gemini processes and indexes all source content

Question

You ask a question about your material

Source Search

Model searches exclusively within your uploaded sources

Cited Answer

Response with numbered citations linking to exact passages

Upload Sources

PDFs, websites, YouTube, audio, Google Docs, Slides

Indexing

Gemini processes and indexes all source content

Question

You ask a question about your material

Source Search

Model searches exclusively within your uploaded sources

Cited Answer

Response with numbered citations linking to exact passages

NotebookLM (Source Grounded)

Knowledge source

Only your uploaded documents

Hallucination risk

Dramatically reduced

Citations

Exact passage in your documents

Scope

Limited to your material

Best for

Research, study, professional analysis

General Purpose Chatbots

Knowledge source

Entire training dataset + web

Hallucination risk

Always present

Citations

Web URLs or none

Scope

Broad, general knowledge

Best for

Open ended questions, creative tasks

The constraint is the feature

NotebookLM's inability to answer questions outside your sources is not a weakness. It is the core design principle that makes it trustworthy for professional and academic use. If you need general knowledge answers, use Gemini, ChatGPT, or Claude. If you need verified answers from specific documents, use NotebookLM.