What is Lisp?

Lisp is one of the languages called as "functional", frequently used in Artificial Intelligence.

Several Lisp interpreters :

• Common Lisp is probably the most used interpreter, and it is available for several operating systems. Its site is clisp.sourceforge.net/
• TL3 is another Lisp interpreter, which includes a Graphics Toolkit and is also multiplaftorm. Get it at www.research.att.com/~leonb/TL3/
• VSLisp is atvslisp.sourceforge.net/

And you can easily find Lisp tutorial. For example, you can try this one:
 http://www.cs.utsa.edu/research/AI/cltl/common-lisp-tutorial.html#Binding