A new branch is based upon an existing commit within the repository. It is entirely up to you to determine and specify which commit to use as the start of the new branch. Git supports an arbitrarily complex branching structure, including branching branches and forking multiple branches from the same commit.
The lifetime of a branch is, again, your decision. A branch may be short-lived or long-lived. A given branch name may be added and deleted multiple times over the lifetime of the repository.
Once you have identified the commit from which a branch should
start, simply use the git branch command. Thus, to create a new branch off the
HEAD of your current branch for the purposes of
fixing Problem Report #1138, you might use:
git branch prs/pr-1138
The basic form of the command is:
starting-commit is specified,
the default is the revision committed most recently on the current
branch. In other words, the default is to start a new branch at the
point where you’re working right now.
Note that the git branch command merely introduces the name of a branch into the repository. It does not change your working directory to use the new branch. No working directory files change; no implicit branch context changes; no new commits are made. The command simply creates a named branch at the given commit. You can’t actually start work on the branch until you switch to it, as shown later in Checking Out Branches.
Sometimes you want to specify ...