You can clone with
HTTPS or Subversion.
Welcome to the joomla-platform wiki!
Developers intending to contribute code to the Joomla! core should sign the Joomla! Contributor Agreement.
Running Unit Tests
Contributing to the Joomla Platform
Platform Examples & Tutorials
Joomla! Developer Network
Joomla! Platform Mailing List
How to set up Git on a Mac, Windows or Linux.
Pro Git is a good book available online and in multiple offline formats (PDF, ePub and Mobi).
The Git Community Book is another useful, online reference.