GTD-PHP is one of many possible tools for use with the productivity solution(s) described by David Allen in his book Getting Things Done.

The basic idea behind his book is that you are at your most productive when you have a clear mind. His solution to "clearing your head" is to have a comprehensive, trusted, externalized organizational system to track everything in your life. Once you do so, your mind can let go of all the little things it previously spent a great deal of time tracking and repeatedly reminding. Only then can you truly focus on the task at hand, which should dramatically increase productivity. However, if your external tracking system is not complete and up to date, your mind will take back the task of worrying and nag you about things you could be or should be doing. That will continually distract you and cause stress.

Installation of GTD-PHP requires a computer running a web server, such as Apache, with PHP & MySQL. It can be installed locally, on a memory stick, on an externally available web server, or a shared hosting site.