From the Twisted Philosophy FAQ:
  Twisted is a project that is basically an abstract Python networking
  library. It contains a low-level (but high-level) networking infrastructure
  (twisted.internet), a Remote Object Thingy[TM] (twisted.spread.pb), a web
  server (twisted.web), and a multi/single-player interactive fiction engine
  (twisted.reality), amongst many other things.

From the (more lucid?) README:
  Twisted is an event-based framework for internet applications.  It includes
  a web server, a telnet server, a multiplayer RPG engine, a generic client
  and server for remote object access, and APIs for creating new protocols.

Twisted is based on an unconventional and somewhat Twisted design philosphy:
  http://twistedmatrix.com/page.epy/twistedphil.html

WWW: http://twistedmatrix.com/

-- Johann Visagie <wjv@FreeBSD.org>