Google announced Discover Sources for NotebookLM on April 2, 2025. The feature let users describe a topic, review up to 10 recommended web sources with short explanations of their relevance, and add selected sources to a notebook with one click. It was designed to help people build a starting reading list—not to replace NotebookLM’s existing ability to use web pages they supplied themselves.
How Discover Sources worked
In Google’s launch description, the workflow began inside a NotebookLM notebook. A user opened the Sources panel, selected Discover, and entered a topic or described what they wanted to learn. NotebookLM then gathered what Google described as hundreds of potential web sources, selected relevant results, and presented up to 10 recommendations. Each recommendation included an annotated explanation of why it might be useful.
- Open a notebook and go to its Sources panel.
- Select Discover and describe the topic you want to explore.
- Review the recommended sources and their relevance notes.
- Add the sources you want to use to the notebook with one click.
Google also described an “I’m Feeling Curious” button that suggested a random topic as a way to try the discovery feature. The figures—hundreds of candidates and up to 10 recommendations—come from Google’s April 2025 product announcement; they are not an independent audit of the search process or a guarantee that every topic will return 10 useful results.
What happened after sources were added
Discover Sources was a way to find and collect material. Once sources were in a notebook, users could continue with NotebookLM’s source-based tools: read the original material, ask questions in chat, and use features Google cited such as Briefing Docs, FAQs, and Audio Overviews. The resulting notebook could also be used for notes and source-linked answers.
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How it differed from NotebookLM’s earlier web support
Discover Sources did not introduce web pages as a source type. In June 2024, Google had already said NotebookLM supported web URLs alongside Google Slides, Google Docs, PDFs, and text files. Google also described inline citations that lead readers to supporting passages in sources. The April 2025 addition addressed a different step: finding possible sources when a user had not already gathered them.
Discover Sources and later NotebookLM research features
Google subsequently announced more involved research capabilities. These are later product announcements, not features or access terms to read back into the April 2025 Discover Sources launch.
| Capability | Google announcement | Process and output described |
|---|---|---|
| Web URL support | June 6, 2024 | Users could add web URLs as sources; Google also described inline citations to supporting passages. |
| Discover Sources | April 2, 2025 | Describe a topic, review up to 10 recommendations with relevance notes, and add selected sources to a notebook. |
| Deep Research | November 13, 2025 | Google described a research plan, browsing across hundreds of websites, and an organized, source-grounded report with recommended sources. It presented Fast Research and Deep Research as two research styles. |
| Chat-led web research upgrades | July 16, 2026 | Google described starting research from loose ideas in chat and using Google Search to find and add relevant web sources. |
The comparison reflects Google’s launch descriptions, not an independent performance test. Discover Sources was framed as a quick way to assemble a notebook’s initial source set; Deep Research was framed as a more autonomous workflow for complex online research that produces a report as well as recommended sources.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What Google said about rollout and availability
For the April 2025 announcement, Google said Discover Sources would roll out to NotebookLM users over about a week. That was the rollout expectation stated at launch, not a current account-by-account availability check.
For the separate July 2026 research upgrades, Google said the rollout was global on the web for Google AI Ultra users and Workspace business customers with AI Expanded Access, with broader expansion planned. Those conditions describe that update as announced; they do not establish eligibility for every NotebookLM feature, account, or location today.
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