On Software Build Systems

A Software Build System is a program that accepts a series of input files:

• Code (Java)
• External Dependencies (JAR files)
• Resources (HTML, translations, CSS, JavaScript, images, ...)

And outputs a series of files in another location (to allow building from read-only sources):

• Archives (WAR, or JAR) (compiled or minimized code and minimized HTML and CSS)
  

Apache Maven is a great build system as it can automatically upgrade and download external dependencies and uses a clear folder structure shared by most projects.