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.
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.
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.
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.
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.