Concept
Phing is a build tool written in PHP. It is based on Apache Ant and uses the same type of XML configuration to configure it. It is actually perfect to combine it with a automated build tool like Jenkins, Hudson, Bamboo, Xinc, Sismo, or many other Continuous Integration (CI) servers.
Motivation
We all hate to repeat tasks over and over again and repeating tasks, we usually make mistakes sooner or later. It is normal human behavior and just happens. In order to avoid all that, use a build tool and automate your stuff! It will decrease your error rate radically and just makes fun to use it.
Same is true for a CI server. It is awesome if all those tasks like testing, static code analysis, API documentation generation, packaging or bundling gets done in the background automatically.
Deployment
You can even go that far to use your build process to do the deployment as well. Deployment might be everything involved in packaging, deploy to other servers or customers up to installing, configuring or updating you project or product. Phing supports tasks like ZIP, GZip, FTP, SCP, rsync, SSH, DbDeploy, PEAR, Composer, and many many other commands which you might want to use. Everything that is not included can be easily extended in you favorite language: PHP.