the biggest conceptual difference between git and svn is that in git, your repository is local. So when you commit, your commit is private - nobody else knows about it. In order to synchronize with everybody else, you need to 'push' to the remote repository

The following link gives a pretty good explanation about working with remote repositories:
http://git-scm.com/book/en/Git-Branching-Remote-Branches

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Barak