Branches are created based on another branch, generally master. The command
git branch <new branch name> <starting branch> takes an existing branch and creates a separate branch to work in. At this point both branches are identical.
To switch to a branch you use the
git checkout <new branch name> command.
Create and checkout a new branch called 'new_branch'
git checkout -b <new branch name> will create and checkout the newly created branch.