The default branch is considered the "base" branch in your repository, against which all pull requests and code commits are automatically made, unless you specify a different branch.
Your default branch is named
master. If you have admin rights over a repository on GitHub, you can change the default branch on the repository.
On GitHub, navigate to the main page of the repository.
In the repository's right sidebar, click Settings.
Change the default branch using the default branch dropdown.
You can only switch between branches that already exist on GitHub. To create a new branch through the UI, see "Creating and deleting branches within your repository".