Make sure you read the Introduction Chapter of this series for a better understanding of the below. Developers might be interested in installing CiviCRM from our svn repository
Some of the important directories under CiviCRM svn root are:
CRM: Most of the CiviCRM specific source code is stored in the directory. This directory is further sub-divided into other directories based on functionality (Core, Utils, Contact, Contribute, Mailing etc). xml: CiviCRM schema and the base Data access objects (DAO) are automatically generated from a simplified xml scheme which contains a fair amount of sql and type information. This makes it relatively easy for us to change the sql code, figure out what changes were made in a version and add meta information to a table within PHP.