Microsoft 365 Copilot is an AI assistant built into Word, Excel, PowerPoint, Outlook, and Teams that can draft emails, summarize meetings, build presentations, and answer questions about your own files and data. It launched for large businesses in November 2023 at $30 per user per month and expanded to smaller businesses in early 2024.

Announced March 16, 2023, Microsoft 365 Copilot combines large language models (LLMs) with Microsoft Graph — a system that connects to a user's emails, calendar, files, and chats — so the AI can reference personal and organizational context when generating responses. An Early Access Program ran with around 600 companies before the enterprise launch. In November 2024, Microsoft added Copilot Actions, which automates repetitive multi-step tasks. A bug disclosed in February 2026 exposed some customers' confidential emails to the Copilot AI system. Internal data can be inadvertently surfaced if file permissions are not carefully managed.