NotebookLM has introduced a "Deep Research" feature that automatically searches hundreds of websites and compiles a sourced report. It now supports a wider range of file types, including Google Sheets, Word documents, and images of handwritten notes, allowing users to upload materials without needing to convert them to PDFs. Users can input a topic and choose between "Fast Research" for a brief overview or "Deep Research" for a more detailed exploration. The update consolidates user uploads, external web research, AI-generated summaries, and analysis into one space, and will be rolled out to all users within the next week, though some may experience delays. Users are advised to verify the relevance and credibility of the gathered materials.