A GitHub issue is a tracked unit of work within a repository: a bug report, feature request, or task. Issues have titles, descriptions, labels, assignees, milestones, and a comment thread where collaborators discuss the work. They can reference commits and pull requests, creating two-way links between planning discussions and the code changes that address them. Issues serve as the planning layer for repository work, making it possible to track what needs to be done, who is responsible, and what progress has been made. When an issue is closed by a pull request, the link between discussion and resolution is preserved in the project history.