This lesson teaches you how to use several valuable Visual LISP ® debugging tools that speed up the development of AutoLISP ® programs. You will also learn the difference between local and global variables, and when to use them. Your program will become more active—prompting users to enter some information. The information will be stored in a list and you'll begin to understand the power of using lists within your AutoLISP programs. After all, LISP got its name because it is a LISt Processing language.