A notebook is a folder you fill with the papers for one job. The helper only reads what's in that folder, so its answers stay about that job.
Copilot Notebooks let you collect files, pages, links and more in one place, then ask Copilot about them. Copilot answers only from what you've added, and only what you have permission to open. I use the idea as a decision file: everything the decision rests on, in one place.
Notebooks are scoped grounding workspaces in the Microsoft Copilot app and OneNote. Copilot grounds only on added references within user permissions: up to 300 for licensed users (shared locations are searched for the 300 most relevant files), 50 for Copilot Chat users. Custom instructions and audio overviews are supported. Deletion is currently permanent.
What a notebook is
Microsoft describes Copilot Notebooks as AI-powered workspaces where you bring together your content and sources, so Copilot can give more relevant answers. You create a notebook, add references, and ask questions. Microsoft's support page says the answers are "based only on the references you've added to your notebook".
References can be Word, PowerPoint, Excel and PDF files, Copilot Pages, Loop files, text files and OneNote pages. Licensed users can also add SharePoint sites, document libraries or folders, and Microsoft says Copilot then uses the supported files there that you have permission to open. Public web pages can be added as links, as long as they don't need a sign-in.
Who can use it
Notebooks are available to people with a Microsoft Copilot licence and to Copilot Chat users, with differences. Microsoft's support pages say licensed users can add more than 300 references but only the first 300 are used for grounding. Copilot Chat users can add up to 50, and all 50 are used. Teams content, SharePoint and OneDrive locations, and internal URLs are listed as premium sources for licensed users.
The account also needs a SharePoint or OneDrive service plan to create notebooks, because they're stored in a SharePoint Embedded container that belongs to the user.
Why I think of it as a decision file
Most decisions rest on a handful of documents: a policy, a quote or two, some notes from a meeting, maybe a spreadsheet. In normal Copilot chat, the model searches broadly and you can't always tell what it relied on. In a notebook, the list of references is right there. That gives you something close to an evidence file for the decision.
It also helps with the questions people ask later. If someone asks "what did we know when we chose this supplier?", the notebook's references are a reasonable answer, as long as nobody has changed them since. Microsoft notes that references stay current as the underlying files change. That's useful while you're working, but for a record of what you knew at the time I'd keep a dated summary in a decision record.
A worked example
This scenario is illustrative. A facilities manager has to choose between repairing and replacing a building's boiler. She creates a notebook called "Boiler decision, autumn 2026" and adds:
| Reference | Type |
|---|---|
| Two contractor quotes | |
| Five years of maintenance logs | Excel |
| The building's energy policy | Word |
| A manufacturer's public product page | Link |
She sets a custom instruction: "Answer in plain English and say which reference each point comes from." Then she asks, "Compare the 10-year cost of repair and replacement using only these references, and list what's missing." The second half of that prompt is the useful part. If Copilot says there's no energy price assumption, she knows to add one before deciding.
Things to know before you rely on one
Microsoft lists some current limits. Notebooks can't create charts or images directly. When you add a shared location, Copilot picks up to 300 relevant files from it for each prompt, so if a specific file matters, add it directly. And deleting a notebook is currently permanent: Microsoft says neither users nor administrators can recover a deleted notebook, and that a recycle bin is in development.
What I'm still checking
I haven't tested how reliably a notebook says "that isn't in the references" when asked something outside them. I'd test that with a question I know the answer to before trusting it on a real decision.
Sources
- Microsoft Support, How Microsoft Copilot Notebooks works, accessed 11 October 2026.
- Microsoft Support, Add references to your Microsoft Copilot Notebook, accessed 11 October 2026.
- Microsoft Support, How to share a Microsoft Copilot Notebook, accessed 11 October 2026.
- Microsoft Learn, Overview of Copilot Pages and Copilot Notebooks storage, accessed 11 October 2026.