How is a tag different from a branch in Git? Which should I use, here?

git version-control branch git-branch git-tag
Bialecki picture Bialecki · Sep 21, 2009 · Viewed 218.1k times · Source

I am having some difficulty understanding how to use tags versus branches in .

I just moved the current version of our code from to , and now I'm going to be working on a subset of that code for a particular feature. A few other developers will be working on this as well, but not all developers in our group are going to care about this feature. Should I be creating a branch or a tag? In what situations should I be using one versus the other?

Answer

Jakub Narębski picture Jakub Narębski · Sep 22, 2009

From the theoretical point of view:

  • tags are symbolic names for a given revision. They always point to the same object (usually: to the same revision); they do not change.
  • branches are symbolic names for line of development. New commits are created on top of branch. The branch pointer naturally advances, pointing to newer and newer commits.

From the technical point of view:

  • tags reside in refs/tags/ namespace, and can point to tag objects (annotated and optionally GPG signed tags) or directly to commit object (less used lightweight tag for local names), or in very rare cases even to tree object or blob object (e.g. GPG signature).
  • branches reside in refs/heads/ namespace, and can point only to commit objects. The HEAD pointer must refer to a branch (symbolic reference) or directly to a commit (detached HEAD or unnamed branch).
  • remote-tracking branches reside in refs/remotes/<remote>/ namespace, and follow ordinary branches in remote repository <remote>.

See also gitglossary manpage:

branch

A "branch" is an active line of development. The most recent commit on a branch is referred to as the tip of that branch. The tip of the branch is referenced by a branch head, which moves forward as additional development is done on the branch. A single git repository can track an arbitrary number of branches, but your working tree is associated with just one of them (the "current" or "checked out" branch), and HEAD points to that branch.

tag

A ref pointing to a tag or commit object. In contrast to a head, a tag is not changed by a commit. Tags (not tag objects) are stored in $GIT_DIR/refs/tags/. [...]. A tag is most typically used to mark a particular point in the commit ancestry chain.

tag object

An object containing a ref pointing to another object, which can contain a message just like a commit object. It can also contain a (PGP) signature, in which case it is called a "signed tag object".

Related questions

View a file in a different Git branch without changing branches

Is it possible to open a file in a git branch without checking out that branch? How? Essentially I want to be able to open a file in my github pages branch without switching branches all the time. I don't …

Read More
git remote prune – didn't show as many pruned branches as I expected

From the man page: Deletes all stale tracking branches under <name>. These stale branches have already been removed from the remote repository referenced by <name>, but are still locally available in "remotes/<name>". So …

Read More
How do I rename my Git 'master' branch to 'release'?

We would like to enforce a new policy for our projects that the master branch now be called the release branch to ensure it is more clear as to how the branch should be used. Naturally, we will have develop …

Read More