Ted Nelson's Xanadu is a commercial dream project for a world-wide _(unified) electronic library.

Official site: <A HREF="http://www.xanadu.net/">xanadu.net</a> and <A HREF="http://www.xanadu.com.au">Australian home</a>

Now it's become Free software <A HREF="http://www.udanax.com/">Udanax</a>.

It is also critiqued by the _(Electronic Labyrinth|http://jefferson.village.virginia.edu/elab/hfl0155.html).

See also _(Sunless Sea - The Xanadu Cyberarchaeology Project|http://www.sunless-sea.net/) and the _(Abora|http://www.abora.org/) project.

Xanadu failed, and was vanquished by the WWW, because it lost all its time trying to adapt technology to intellectual property law, instead of developing the best technology, and letting law adapt to it (by dropping inapplicable intellectual property). <span class="comment">Actually, the Xanadu implementations didn't include any intellectual-property related features, although Ted Nelson surely wasted lots of time on that kind of issue.</span>

Despite its failure, the Xanadu Project still produced some useful data structures such as _(tumblers|http://www.sunless-sea.net/wiki/Definitions?word=tumbler), _(enfilades|http://www.sunless-sea.net/wiki/Definitions?word=enfilade), and _(the Ent|http://www.sunless-sea.net/wiki/Definitions?word=ent) (as well as humbers (a type of bignum), etc.).