The fundamental means of launching a separate line of development in a software project is a branch. A branch can be used to keep an old version of the project alive. A branch can be used to encapsulate a development phase or the development of a single feature or bug fix.

Branch names are pretty arbitrary but there are many characters not allowed or not allowed at the beginning or end.

There can only be one current branch within the git repository at any given time. The current branch determines which files are checked out in the working directory. It is also often an implicit operand in Git commands (such as the target of a merge).

The most recent commit on a branch is called the tip or {{c1::head}} of the branch. A branch/branch name can be thought of as a pointer to a particular {{c1::commit}}. To introduce a new branch to the repo within checking it out as the current branch, use the git branch command. This command also lists the branch names found in the repo if not passing a branch name argument. The git show-branch also can be used to view the branches and provides more detailed output than git branch.

The git checkout command changes the current branch. If you have local changes, Git will issue an error message and let you know that you need to commit you changes first (adding it to the index is not sufficient). You can use the -f option to tell Git to check out the other branch anyway which will overwrite your local changes.

If you check out a random commit, Git creates a sort of anonymous branch for you called a {{c1::detached HEAD}}. It also does this when starting a git bisect operation or the git submodule update command.

The git branch command with the -d or -D option can be used to delete a branch. If deleting the branch were to delete a commit that would be lost since it had not been merged into main, Git will issue an error when using -d but the -D option will override Git's safety check. When a branch is deleted, the branch name is gone. It may be possible to recover the commits (git reflog would be the command to get that started) but commits with no references to them will eventually be collected as garbage.