About outside collaborators
An outside collaborator is a person who is not a member of your organization, but has access to one or more of your organization's repositories. You can choose the level of access to grant for each outside collaborator. When you add an outside collaborator to a repository, you'll also need to add them to any forks of the repository you'd like them to access.
Unless you are on a free plan, adding an outside collaborator to a private repository will use one of your paid licenses. For more information, see "About per-user pricing."
Organizations that use GitHub Enterprise Cloud can restrict the ability to invite collaborators. For more information, see Setting permissions for adding outside collaborators in the GitHub Enterprise Cloud documentation.
If your organization requires two-factor authentication, all outside collaborators must enable two-factor authentication before accepting your invitation to collaborate on a repository. For more information, see Requiring two-factor authentication in your organization.
Outside collaborators cannot be added to a team, team membership is restricted to members of the organization.
Adding outside collaborators to a repository
You can give outside collaborators access to a repository in your repository settings. For more information, see Managing teams and people with access to your repository.