GitHub Copilot Explained: Completions, Chat and Agent Mode
GitHub Copilot is the AI coding assistant from GitHub and Microsoft. It began as an autocomplete tool and now covers inline suggestions, a chat assistant, multi-step agent work inside the editor, and tasks handed off to run in the cloud. This guide explains each piece, where it runs, and how to start without losing control of your codebase. Check GitHub’s features page for the current list, because support changes between releases.
⚡ Quick facts
- What it is: GitHub’s AI assistant for writing, explaining and changing code
- Where it works: VS Code, Visual Studio, JetBrains IDEs, Xcode, Eclipse, Vim and Neovim, plus GitHub.com and mobile
- Main modes: Inline completions, Copilot Chat, agent mode, and a cloud agent for delegated tasks
- Best for: Developers who want AI inside the editor they already use
- Check first: Which plan you have, since features and limits differ by plan
The pieces of Copilot
Inline completions
As you type, Copilot proposes the rest of a line or a block of code, and you press Tab to accept. GitHub’s documentation lists support in several editors, including Visual Studio Code, Visual Studio, JetBrains IDEs, Xcode, Eclipse and Vim or Neovim. A newer feature, next edit suggestions, tries to predict where you will edit next and propose the change there. GitHub marked it as a preview feature in its docs, so availability depends on your editor.
Copilot Chat
Chat answers coding questions in a side panel. It is available in supported IDEs, on the GitHub website, in GitHub Mobile and in Windows Terminal. Typical uses are explaining unfamiliar code, suggesting a fix for an error message, writing tests for a selected function and drafting a commit message or pull request summary.
Agent mode
In editors that support it, agent mode takes a larger goal, edits several files, runs terminal commands and works through the errors it causes. It differs from chat in that it acts on your project instead of only suggesting text. That makes review more important, not less.
Cloud agent
Some plans let you hand a task from a GitHub issue to an agent that works in the background and opens a pull request for you to review. It fits well-scoped chores such as small bug fixes or test coverage, and poorly fits vague design questions.
Getting started
- Sign in to GitHub and turn on Copilot for your account or organization. Your plan decides which features you see, so check the details on GitHub’s Copilot page.
- Install the Copilot extension in your editor and sign in.
- Write a comment describing a small function and see what Copilot suggests.
- Open Chat, select a block of code and ask it to explain what it does.
- Move to agent mode only after you are comfortable reviewing its changes.
Using it well
- Write specific comments and names. Copilot works from context, so a clear function name and docstring produce better suggestions than a vague one.
- Review everything. Suggestions can contain bugs, outdated API usage or insecure patterns. Treat them like a pull request from a new teammate.
- Write tests first for risky logic. Tests catch confident but wrong code.
- Know your organization’s policy. Companies often restrict which AI tools can see their source code. Ask before using it on work repositories.
Copilot compared with other options
Copilot’s main advantage is reach: it plugs into the editors most teams already use and into GitHub itself. Editors built around AI, such as Cursor, go further on multi-file edits, while terminal agents like Claude Code suit people who prefer reviewing diffs in git. Our explainer on what AI agents are helps put agent mode in context, and the Model Context Protocol article covers how coding tools connect to outside data and services. Microsoft’s separate Copilot assistant for Windows and Microsoft 365 is a different product from GitHub Copilot, even though the names are similar.
Official source: GitHub Copilot features documentation. Features, limits and prices change often, so confirm details there before you rely on them.
Frequently asked questions
Is GitHub Copilot free?
GitHub has offered different plans over time, including options for individuals, students, open-source maintainers and organizations. Because this changes, check the pricing and eligibility on GitHub’s Copilot page rather than relying on a figure in an article.
Which editors does GitHub Copilot support?
GitHub’s documentation lists Visual Studio Code, Visual Studio, JetBrains IDEs, Azure Data Studio, Xcode, Vim or Neovim and Eclipse for completions, with chat available in most major IDEs. Specific features can vary by editor.
What is the difference between Copilot Chat and agent mode?
Chat answers questions and suggests code that you copy or apply. Agent mode acts on your project: it edits several files, runs commands and tries to fix errors, so you review a set of changes rather than a single snippet.
Is Microsoft Copilot the same as GitHub Copilot?
No. GitHub Copilot is a coding assistant. Microsoft Copilot is a general assistant built into Windows, Edge and Microsoft 365. They share a brand but are separate products.
Can Copilot write insecure code?
Yes. Like any AI coding tool, it can produce code with bugs or security problems. Review suggestions, run tests and use your normal code-scanning and review process.