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

Answer 1

Tinkertoys, the perfect modelling tool for a Directed Acyclic Graph Node

Git For Ages 4 And Up is a fun talk on Git and provides surprisingly useful visualizations using Tinkertoys.