Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.Qi is a functional programming language developed by Dr Mark Tarver and introduced in April 2005 under the GNU GPL license. An upgraded version was reimplemented and issued as Qi II in November 2008. Qi II is currently free for personal and educational use and a proprietary license for producing closed source is included in the language guide available from the home site. Qi is written in Lisp. It includes most of the features common to modern functional programming languages such as pattern-matching, currying, partial applications, guards and (optional) static type checking. Qi was developed as part of the L21 project, which aims to modernise Lisp to meet the challenges of twenty-first century computing. In his lecture, Dr Tarver outlined a series of current challenges to Lisp which he argued were damaging to the wider use of the language. Specifically he identified Common Lisp''s lack of pattern-matching, inconsistency with respect to lambda calculus theory (partial applications being missing), procedural contamination and lack of static typing.