Phing is a PHP build process that uses XML , ANT style syntax.
At some point in development, the choice is made to begin professional work. If more than 1 developer contributes to the effort, then an the easy mode of keeping in sync with that person and, in the future, others that may join the effort is required. Because not all developers are alike, and not all hosting providers are alike, you must have a solid build process of your code. The build process automates the routines that every developer must do, either daily, hourly, or with every code change as well as when code is pushed into client facing distributions. Phing is an XML to PHP build process that imitates the ANT build process that many development shops are used to. As a PHP developer, Phing is much easier for me to work with and get things done, as well as keeps things simple when needing to update the build process.