The process called ai.exe, whose file description reads "Artificial Intelligence (AI) Host for the Microsoft Windows Operating System and Platform x64," is tied to Microsoft 365 and Office apps rather than to Windows itself. A Microsoft Community support specialist described it on January 31, 2025 as the helper behind AI-driven Office features such as grammar corrections. Microsoft's separate toolkit for AI built into Windows apps is named Microsoft Foundry on Windows, and it does not use that file name.
Key takeaways
- ai.exe appears in Task Manager under Office apps. Reports from 2023 place it in the Office installation folder, and a Microsoft support specialist links it to Office AI features.
- Microsoft has not published a dedicated reference page for the file, so most explanations come from community replies and tech press.
- Copilot can be switched off per app in Word, Excel, PowerPoint, and OneNote on Windows through a setting Microsoft documents.
- Windows has its own local AI layer, Microsoft Foundry on Windows, which is a developer toolkit and not a single background process.
- A process with this name should still be checked for a Microsoft digital signature before anyone trusts or deletes it.
What the "AI Host" label refers to
The label comes from a file description, the text Windows shows next to a program in Task Manager. The Microsoft Q&A thread where a Microsoft Community Support Specialist explained it was started by a user who saw ai.exe using memory while offline. The specialist's reply said the process supports AI features in Office applications, processes input from them, and may stay loaded in the background so the next launch is quicker. The reply was community support, not a product manual, and it gave no file path.
Earlier reporting is more specific. Windows Latest wrote on April 10, 2023 that Word, Outlook, and PowerPoint hand most local AI functions to ai.exe, which hosts a library called ai.dll, while a second program, aimgr.exe, manages the instances. It placed the file in the Office folder under Program Files, in a path ending in rootvfsProgramFilesCommonX64Microsoft SharedOFFICE16. The same article said Microsoft had not publicly documented the change and treated any link to Microsoft 365 Copilot as speculation. That caveat still applies: the reporting describes behavior, not Microsoft's intent.
Three things that share the word AI on a Windows PC
Searches for an AI host on Windows tend to mix up separate components. The table separates them by what Microsoft's own documentation says. It is a simplified orientation, not a full inventory of Windows processes.
| Name | What it is | Where it applies |
|---|---|---|
| ai.exe | Office-side process described as an "AI Host," linked by a Microsoft support specialist to AI features in Office apps | PCs with Office or Microsoft 365 desktop apps |
| Windows AI APIs | Ready-made local models and APIs, such as text recognition and image description, that apps can call | Mostly Copilot+ PCs, with a few APIs on other Windows 11 hardware |
| Foundry Local | Runtime for running open language and speech models on the device | Windows 10 and later, performance varies by hardware |
| Windows ML | Framework built on ONNX Runtime for running models an app developer finds or trains | Windows 10 and later |
How Windows itself runs AI locally
Microsoft's developer documentation, updated in 2026, groups local AI under the name Microsoft Foundry on Windows. Its decision guide tells app developers to check the built-in Windows AI APIs first, then Foundry Local for language and speech models, then Windows ML for custom models. The pieces can be combined in one app. Model files for the first two are hosted by Microsoft, fetched at runtime, and shared across apps, so each app does not carry its own copy.
Much of this depends on hardware. Microsoft defines Copilot+ PCs as Windows 11 machines with a neural processing unit (NPU) capable of more than 40 trillion operations per second. The developer guide says the NPU shows up in Task Manager next to the CPU and GPU, and that Windows ML picks the fastest available accelerator and falls back to the GPU or CPU if needed. None of this documentation names ai.exe, which fits the picture of an Office component and a Windows platform that happen to share a theme.
What AI Office features do, and how to turn them off
Microsoft's support page on turning off Copilot in Microsoft 365 Family and Personal subscriptions lists the controls. In Word, Excel, PowerPoint, and OneNote on Windows, the path is File, Options, Copilot, then clearing Enable Copilot and restarting the app. The page says the "Enable Copilot" checkbox arrived on March 13, 2025 in Word 2412, Excel 2501, PowerPoint 2501, and OneNote 2502, and that an Outlook toggle followed on June 3, 2025. Where the checkbox is missing, the page points to the Account Privacy setting for experiences that analyze content, with the side effect that features such as text predictions and PowerPoint Designer also stop. The page covers personal accounts; settings are not available for work or school accounts.
Whether switching these off stops ai.exe from loading was not confirmed in any source reviewed. The Microsoft specialist's own suggestions were to close Office apps, review background-app permissions, or remove Office as a last resort.
Checking a process called ai.exe
- Open Task Manager, right-click the process, and choose Open file location.
- Confirm the folder is inside the Microsoft Office installation, not a user folder or temporary directory.
- Open the file properties and check that the Digital Signatures tab shows Microsoft Corporation.
- Compare the file description with the text quoted above.
- If any of these checks fails, run a scan with the installed security software before deleting anything.
This article gives general information and is not security or IT support advice. An organization's administrator or Microsoft Support is the right contact for managed devices.
FAQ
Is ai.exe a virus?
Not by itself. A Microsoft support specialist described it as an Office-related process, and the file-description check above helps tell a genuine copy from an imitation. A signed file in the Office folder is expected; the same name in another folder deserves a scan.
Does every Windows PC run an AI host?
No source confirms that. The 2023 report said the file arrives through Office updates, which implies PCs without Office would not have it. Windows features that use an NPU belong to a separate system and depend on the hardware.
Can the AI host be disabled?
Copilot can be turned off per app in several Office programs through documented settings. No source reviewed documents a switch that targets ai.exe directly.
Does Windows send data to the cloud for these AI features?
It depends on the feature. Microsoft's documentation separates local AI, which runs on the device, from cloud AI models, so the answer is set by the specific feature and the account type. Privacy statements for each product are the place to check.
Related reading
- AI software available for Windows PCs
- How neural networks work
- Canadian rules that touch AI products
- A learning path for AI basics
More in AI Tools and Industry.
Last verified: October 2026
Sources
- Use local AI with Microsoft Foundry on Windows, Microsoft Learn, 2026
- Copilot+ PCs developer guide, Microsoft Learn, 2026
- Reply by a Microsoft Community Support Specialist to a question on ai.exe, Microsoft Q&A, January 31, 2025
- How to turn off Copilot in Microsoft 365 Family and Personal subscriptions, Microsoft Support, 2025
- Microsoft 365 quietly adds Artificial Intelligence (AI) Host to Windows 11, Windows 10, Windows Latest, April 10, 2023