GitHub Copilot is the world's most widely adopted AI coding assistant, developed by GitHub in partnership with OpenAI. It has evolved from a simple code completion tool into a fully agentic development partner with the introduction of Agent Mode and Model Context Protocol (MCP) support. Agent Mode can independently translate ideas into code, automatically identifying necessary subtasks and executing them across multiple files. The tool supports Plan mode, which lets developers review and approve a blueprint before the agent starts coding, and includes a Coding Agent that can work on tasks autonomously in the background. Since September 2025, Copilot delivers 2x higher throughput, 37.6% better retrieval, and an 8x smaller index size for faster, more accurate results. GitHub Copilot operates on a premium request system where different models and features consume varying amounts of credits. It supports multiple AI models including GPT-4o, Claude Sonnet, and Gemini, giving developers flexibility to choose the best model for each task. Enterprise features include organization-wide policy management, IP indemnity, and audit logs.