What are the core concepts of git, github, fork & branch. How does git compare to SVN?

Question

I've been using Github for sometime now but I'm getting a bit confused about some key concepts behind Git.

My background with VCS started with Source Safe and then transitioned into SVN and TFS. I think I'm stuck in the old way of thinking of CVS system, like SVN and TFS.

What is considered server-side and client-side in Git. From what I've understood there isn't a clear distinction between them.

In a technical sense, what does a Fork mean. Is it a "type" of branch?

Wat does a branch mean in git? Is it the same as in SVN?

Also I've been looking for a good visualization of the core concepts of Git, but haven't found any one that works for me.

Answer 1

Here's how to understand Git:

1. Forget everything you know about other VCSs (temporarily!)
2. Read The Git Parable. Really read it though, if you skim, you'll miss stuff and just try to fill in the gaps with your existing SCM knowledge, which is what's throwing you off. In fact, if you really want to understand, read that blog post aloud.

At its core, Git is just a way to save and restore snapshots. Each snapshot has an "ID" (the SHA1), and may have one or more "refs" (pointers) to it. A branch? Just a friendlier name for a particular snapshot. Tags? Same thing. HEAD? That's just a "pronoun" for the current snapshot. Conveniently, these snapshots each come with a description of what changed - this description is the commit message.