Common Lisp is a very powerful but somewhat messy dialect of the *(Lisp) *(programming language). It was intended to unify the many dialects of Lisp, and it has succeeded for the most part in doing so; the only other widely used dialects are scheme and emacs lisp.

It turns out that despite its goal of unification, Common Lisp is actually a very good language. It is my opinion that it is unsurpassed, the best overall language as of now (09-14-2002).

Some features: a powerful (but dangerous) macro system, a class-based object system with multiple-dispatch (_(CLOS)) (and often with a powerful _(meta-object protocol)), an extensive standard library full of rich data structures, and a whole lot more. In addition, there are a number of high quality implementations, free and non-free, available. Some of these implementations output very fast code.

Some misfeatures: there are many constraints placed on the language due to compatibility reasons, not the least of which is the fact that it is a lisp2 (ie, it has a special namespace for functions). Many very intelligent people (_(Fare), _(Kent M. Pitman)) feel that this is not a disadvantage, but I do. I feel the macro system is unnecessarily dangerous and restrictive (in that macros are not first class values like procedures). Nothing huge though.

--_(seaslug)

This sounds like the opinion of most people who don't understand that macro hygeine isn't needed in a lisp2. :-) However the points are correct and there is some lisp possible that should be able to best both Common Lisp and Scheme: each design has very old roots. --_(water)
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<UL CLASS="links">
<LI><A HREF="http://www.cliki.net/">CLiki</a>, a reference wiki site that covers <em>everything</em> below much better than we can.</li>
<LI><A HREF="http://www.lisp.org/">Lisp.org</a> or <A HREF="http://www.alu.org">The Association for Lisp Users</a>.
<LI><A HREF="http://www.xanalys.com/software_tools/reference/HyperSpec/">The Common Lisp HyperSpec</a></li>
<LI><A HREF="http://www-cgi.cs.cmu.edu/afs/cs.cmu.edu/project/ai-repository/ai/html/cltl/cltl2.html">CLTL</a>, <A HREF="http://www.supelec.fr/docs/cltl/cltl2.html">French Mirror</a>, Common Lisp: The Language</li>
<LI><A HREF="http://psg.com/~dlamkins/sl/cover.html">Successful Lisp</a>, an excellent way to learn CL</li>
<LI><A HREF="http://www.apl.jhu.edu/~hall/lisp.html">An Introduction and Tutorial for Common Lisp</a>, a list of CL resources</li>
<LI><A HREF="http://www.paulgraham.com/onlisp.html">On Lisp</a>, we recommend this book for intermediate CL learners.</li>
</ul>
<UL CLASS="implementations">
<LI><A HREF="http://sbcl.sourceforge.net/">SBCL</a>, a very high quality free implementation. Based on CMUCL.</li>
<LI><A HREF="http://www.cons.org/cmucl/">CMUCL</a>, outputs very fast code</li>
<LI><A HREF="http://clisp.cons.org/">CLISP</a>: compiles to portable bytecode, offers mediocre performance.
<ul>
<LI><A HREF="http://www.clisp.org/">Alternate #1</a></li>
<LI><A HREF="http://clisp.sourceforge.net/">Alternate #2</a></li>
<LI><A HREF="http://www.gnu.org/software/clisp/">Alternate #3</a></li>
</ul>
<LI><A HREF="http://www.gnu.org/software/gcl/gcl.html">GCL</a>, the _(GNU) project's free implementation</li>
</ul>