PDE/Build builds plug-ins. It is used behind the scenes during export, and it is used for automated headless builds. The purpose of this page is to answer some of the common questions that arise.
There is a significant amount of documentation in the Eclipse Help system under "Plug-in Development Environment Guide > Tasks > PDE Build". The latest version of Eclipse Help is always available online at help.eclipse.org. Galileo documentation for PDE/Build starts here.