Copilot Extensions Glossary

The following terms are used in the context of Copilot Extensions, and are defined here for clarity.

Agent

A concrete implementation of an AI assistant that can receive user queries and return a stream of response tokens. The combination of an agent + GitHub App is what we refer to as a Copilot Extension.

Copilot Chat

The conversational interface within GitHub Copilot where users can interact with the AI assistant and extensions.

Copilot Extension

A GitHub App with additional access to the Copilot Chat window and Copilot API, allowing for extended functionality in GitHub's Copilot Chat. This is how we will refer to extensions from the perspective of an extension user.

Copilot Extensibility Platform

The system that handles authentication and proxies requests between clients and agent plugins.

Copilot-enabled Visual Studio Code extension

Also known as Visual Studio Code Chat extensions, Copilot-enabled Visual Studio Code extensions are built as a Visual Studio Code extension rather than a GitHub App. These extensions are exclusive to VS Code and can be downloaded from the VS Code Marketplace.

GitHub App

The foundation for a Copilot Extension that provides the necessary infrastructure, permissions, and context from GitHub, such as user, repo and organization metadata.

GitHub Marketplace

The platform where GitHub approved GitHub Copilot Extensions can be listed publicly and discovered by users.

Listed/Published Extension

An extension that appears on the GitHub Marketplace. These extensions must be reviewed and approved by GitHub.

Private Extension

An extension that is only visible and usable by the organization or individual user that created it.

Public Extension

An extension that is visible and installable by any GitHub user or organization.

Skill

A piece of code that retrieves context or executes an action in response to a user’s prompt (e.g., "findIssueByID(id: number)").

Tool/Function Calling

A capability of Copilot's LLM (as well as Open AI’s) that allows them to invoke specific tools or functions. Extension builders can define available tools with parameters, enabling the LLM to select and call appropriate tools to fulfill a user’s request. “Functions” are a subset of “tools” and the “function calling” term will be closing down.

Unlisted Extension

An extension that is not published on the GitHub Marketplace. Builders may develop and distribute public unlisted extensions without requiring review or approval from GitHub. GitHub does not guarantee the security or quality of unlisted extensions.

Verified Creator

A status required for organizations to publish extensions on the GitHub Marketplace.