Two mathematics professors at the University of Illinois at Urbana-Champaign are the authors of Macaulay 2, a powerful software tool that supports "research in algebraic geometry and commutative algebra." The Macaulay 2 home page offers the program's source code free for download, which can be compiled under the UNIX, Windows, or Macintosh operating systems. There is also extensive online documentation, a user's guide, and many detailed examples that provide a solid introduction for new users or a handy reference for experts. For further information, the site has several links to papers that refer to Macaulay 2.