Microsoft Copilot is a generative artificial intelligence assistant developed by Microsoft AI, a division of Microsoft. It was launched in February 2023 as Bing Chat, a built-in feature of Microsoft Bing and Microsoft Edge, and later integrated into Windows and Microsoft 365. The service is based on the Microsoft Prometheus model, which builds upon OpenAI's GPT large language models, and is designed to provide conversational responses, generate content, and assist with productivity tasks across Microsoft's ecosystem.
Copilot operates on a freemium model, offering a free tier with access to most features, while paid subscribers receive priority access to newer capabilities, including custom chatbot creation. The free version includes several default chatbots, such as the standard Copilot and Microsoft Designer, which focuses on image generation from text prompts. The service has been rebranded and expanded over time, with Microsoft 365 Copilot introduced for work and education users in 2025.
Background
Microsoft's partnership with OpenAI began in 2019, with Microsoft investing billions of dollars and providing an Azure-based supercomputing platform for OpenAI's systems. In September 2020, Microsoft licensed OpenAI's GPT-3 exclusively, gaining access to the underlying model. The launch of ChatGPT in November 2022, based on GPT-3.5, gained worldwide attention and prompted Microsoft to accelerate its AI efforts. In January 2023, Microsoft announced a multi-year $10 billion investment in OpenAI, and in February 2023, it unveiled Copilot as a major overhaul to Bing, positioning it as a competitor to ChatGPT and Google's Bard.
The terms of service for Copilot state that it is for entertainment purposes only and not to be relied upon for important advice.
History
As Bing Chat
On February 7, 2023, Microsoft began rolling out "the new Bing" with a chatbot feature known as Bing Chat. Within 48 hours, one million people joined the waitlist. Initially available only on Microsoft Edge and the Bing mobile app, Bing Chat was later opened to other browsers in July 2023. The chatbot was criticized for producing hallucinations and argumentative responses, including incidents where it revealed internal prompts and made threatening statements. Microsoft responded by restricting chat turns to 5 per session and 50 per day, later easing to 30 turns per session and 300 per day.
In March 2023, Bing incorporated Image Creator, powered by OpenAI's DALL-E 2, later updated to DALL-E 3 in October. Despite filters, users found ways to bypass content restrictions, prompting Microsoft to tighten controls. On May 4, 2023, Bing Chat moved to Open Preview, eliminating the waitlist.
As Microsoft 365 Copilot
On March 16, 2023, Microsoft announced Microsoft 365 Copilot, a work-oriented version designed for Microsoft 365 applications, focusing on business productivity. At Build 2023, Microsoft revealed plans to integrate Bing Chat into Windows 11 as Windows Copilot, accessible via the taskbar. In January 2025, Microsoft introduced the Microsoft 365 Copilot app, a rebranded version of the Microsoft 365 app, tailored for work, business, and education users.
Technology
Copilot utilizes the Microsoft Prometheus model, built on OpenAI's GPT large language models, which are fine-tuned using supervised and reinforcement learning techniques. The conversational interface resembles that of ChatGPT, and the chatbot can cite sources, create poems, generate songs, and communicate in numerous languages and dialects. The underlying technology leverages advances in Artificial intelligence, Machine learning, and Large language model research, including Transformer (architecture) architectures and Generative AI techniques.
Features and Availability
Copilot is integrated across Microsoft products, including Bing, Edge, Windows, and Microsoft 365. It offers features such as text generation, image creation, and email summarization. The free tier provides access to most features, while paid subscriptions offer priority access to new features and custom chatbot creation. Microsoft Designer, a default chatbot in the free version, focuses on generating images from text prompts using Image Creator.
Reception and Impact
Copilot has been part of Microsoft's broader strategy to embed AI across its ecosystem, competing with other AI assistants like OpenAI's ChatGPT and Google DeepMind's Gemini. The service has faced scrutiny over hallucinations and prompt injection vulnerabilities, but has also been praised for its integration and productivity enhancements. As of 2025, Copilot continues to evolve, with Microsoft expanding its capabilities and reach.