Defining the mergeability of pull requests
Protected branches are available in public repositories with GitHub Free, and in public and private repositories with GitHub Pro, GitHub Team, GitHub Enterprise Cloud, and GitHub Enterprise Server.
You can require pull requests to pass a set of checks before they can be merged. For example, you can block pull requests that don't pass status checks or require that pull requests have a specific number of approving reviews before they can be merged.
About protected branches
Protected branches ensure that collaborators on your repository cannot make irrevocable changes to branches. Enabling protected branches also allows you to enable other optional checks and requirements, like required status checks and required reviews.
Configuring protected branches
If you're a repository owner or have admin permissions in a repository, you can customize branch protections in the repository and enforce certain workflows, such as requiring more than one pull request review or requiring certain status checks to pass before allowing a pull request to merge.
About required status checks
Required status checks ensure that all required CI tests are passing before collaborators can make changes to a protected branch.
Types of required status checks
You can set up required status checks to either be "loose" or "strict." The type of required status check you choose determines whether your branch is required to be up to date with the base branch before merging.
Enabling required status checks
Repository administrators can enforce required status checks before a branch is merged in a pull request or before commits on a local branch can be pushed to the protected remote branch.
About branch restrictions
Branches within repositories that belong to organizations can be configured so that only certain users or teams can push to the branch.
Enabling branch restrictions
Organization owners and people with admin permissions for organization-owned repositories can enforce branch restrictions so that only certain users or teams are able to push to a protected branch.
About required reviews for pull requests
Required reviews ensure that pull requests have a specific number of approving reviews before collaborators can make changes to a protected branch.
Enabling required reviews for pull requests
Repository administrators can enforce required reviews so that pull requests must have a specific number of approving reviews before they are merged.
About required commit signing
Required commit signing ensures that collaborators can only push verified signed commits to a protected branch.
Enabling required commit signing
Repository administrators can enforce required commit signing on a branch to block all commits that are not signed and verified.