What is the difference between Git and GitHub?
Git is a distributed version control system. It usually runs at the command line of your local machine. It keeps track of your files and modifications to those files in a "repository" (or "repo"), but only when you tell it to do so. (In other words, you decide which files to track and when to take a "snapshot" of any modifications.)
In contrast, GitHub is a website that allows you to publish your Git repositories online, which can be useful for many reasons (see #3).
Is Git saving every repository locally (in the user's machine) and in GitHub?
Git is known as a "distributed" (rather than "centralized") version control system because you can run it locally and disconnected from the Internet, and then "push" your changes to a remote system (such as GitHub) whenever you like. Thus, repo changes only appear on GitHub when you manually tell Git to push those changes.
Can you use Git without GitHub? If yes, what would be the benefit for using GitHub?
Yes, you can use Git without GitHub. Git is the "workhorse" program that actually tracks your changes, whereas GitHub is simply hosting your repositories (and provides additional functionality not available in Git). Here are some of the benefits of using GitHub:
- It provides a backup of your files.
- It gives you a visual interface for navigating your repos.
- It gives other people a way to navigate your repos.
- It makes repo collaboration easy (e.g., multiple people contributing to the same project).
- It provides a lightweight issue tracking system.
How does Git compare to a backup system such as Time Machine?
Git does backup your files, though it gives you much more granular control than a traditional backup system over what and when you backup. Specifically, you "commit" every time you want to take a snapshot of changes, and that commit includes both a description of your changes and the line-by-line details of those changes. This is optimal for source code because you can easily see the change history for any given file at a line-by-line level.
Is this a manual process, in other words if you don't commit you won't have a new version of the changes made?
Yes, this is a manual process.
If are not collaborating and you are already using a backup system why would you use Git?
- Git employs a powerful branching system that allows you to work on multiple, independent lines of development simultaneously and then merge those branches together as needed.
- Git allows you to view the line-by-line differences between different versions of your files, which makes troubleshooting easier.
- Git forces you to describe each of your commits, which makes it significantly easier to track down a specific previous version of a given file (and potentially revert to that previous version).
- If you ever need help with your code, having it tracked by Git and hosted on GitHub makes it much easier for someone else to look at your code.
For getting started with Git, I recommend the online book Pro Git as well as GitRef as a handy reference guide. For getting started with GitHub, I like the GitHub's Bootcamp and their GitHub Guides. Finally, I created a short videos series to introduce Git and GitHub to beginners.
