learn-co-curriculum / git-workflow-branching-terminology

Git: Branching Terminology

Learning Goals

• Identify local branch
• Identify remote branches
• Identify remote tracking branches
• Identify local tracking branches

Introduction

Many developers and organizations use Git branches to keep track of their work. It’s important that we understand how to work with branches on both our local machine as well as on a shared resource, like GitHub. Being able to share branches means that all the advantages of branch-based development are available both for individuals and organizations.

We've gone through the steps of pushing our branches to GitHub, so let's clarify some terminology around different types of branches and related commands.

Identify Local Branch

A local branch is a branch that only we (the local user) can see. It exists only on our computer. The git branch command can show us our local branches:

$ git branch
  * master
  larry-branch
  michelle-branch
  curly-branch

Identify Remote Branches

A remote branch is a branch on a remote repository. Remote repositories have a short name or nickname. By default, when we git clone the remote is called origin. Many Git commands assume that if you don't specify a repo explicitly, you mean origin. When we push our local branch new-branch-name to origin, we and other users can track it. That is, we can retrieve those contents. So we don't have to haul computers around, we can simply grab the code from the remote repository and pick up where we left off!

We can see a list of all the remotes' shortnames with git remote. Usually there is only one, origin, the default. As you get more skilled you might share your code to multiple remotes.

We can see a list of all remote branches — that is all the branches at all the remotes — that Git knows about with git branch -a.

Identify Remote Tracking Branches

A remote tracking branch is a local copy of a remote branch.

When a locally-created branch like new-branch-name is pushed to origin using the git push -u origin new-branch-name command, a remote tracking branch named origin/new-branch-name is created on your machine.

In reverse, when you clone a repository you're given remote tracking branches for all the remote branches. Amazingly, by doing so Git allows you to work with all the remote branches on all the remotes offline. Provided you "freshen" your local repository with git fetch right before you go into the wilderness, you can have years of software development on your laptop (provided you explicitly freshen with git fetch right before, more on that below!).

This remote tracking branch "follows" or "tracks" the remote branch new-branch-name on origin. We can update your remote tracking branch to be in sync, or up-to-date, with the remote branch using git fetch.

Identify Local Tracking Branches

A local tracking branch is a local branch that is tracking another local branch. Most often, the local branch is tracking a remote tracking branch that, in turn, is tracking a remote branch.

This sounds confusing and this is an area that can be really frustrating with Git. Let's suppose you want to work on a branch that someone else pushed up to your remote. After you clone the repo, you want to work on my-friends-branch.

If you do git checkout origin/my-friends-branch Git will:

1. Establish a remote tracking branch called (remotes/origin/my-friends-branch) that points to origin/my-friends-branch
2. Establish a local tracking branch (my-friends-branch) that tracks (remotes/origin/my-friends-branch)
3. Put you "on" the local tracking branch (my-friends-branch)

Because Git can trace how to get from your local tracking branch to the remote tracking branch back to the original remote branch, if you make a commit on this branch and then type git push, Git will send your change to the remote repository so that other collaborators can get your change and build on it! This is the heart of collaboration in Git.

Conclusion

Branching is a very useful tool for working on your own code and sharing code with others. It is common for several developers to share and work on the same source code by referring to the same shared "remote," typically called origin.