Ken Jones, president of Avia Training and Consulting, has spent thousands of hours teaching Tcl to IT professionals. He has more than twenty years of experience training developers through live courses and documentation. As lead instructor at Scriptics, he worked closely with John K. Ousterhout and many other key Tcl developers. Jones coauthored Practical Programming in Tcl and Tk, Fourth Edition (Prentice Hall, 2003).