Devin is an autonomous AI software engineer that can write, debug, plan, and execute complex coding tasks end-to-end using natural language prompts. It operates in a sandboxed environment with tools like a shell, code editor, and browser, enabling it to handle real-world GitHub issues, refactor code, build apps, review PRs, and work on parallel tasks. Devin collaborates with users by reporting progress, accepting feedback, and integrating with tools like Slack and MCP servers.