  PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing
binary stars, built on top of the widely used WD program (Wilson & Devinney
1971). This introductory paper overviews most important scientific extensions
(incorporating observational spectra of eclipsing binaries into the
solution-seeking process, extracting individual temperatures from observed
color indices, main-sequence constraining and proper treatment of the
reddening), numerical innovations (suggested improvements to WD's Differential
Corrections method, the new Nelder & Mead's downhill Simplex method) and
technical aspects (back-end scripter structure, graphical user interface).
While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to
enhance WD by encompassing even more physics and solution reliability. The
operability of all these extensions is demonstrated on a synthetic
main-sequence test binary; applications to real data will be published in
follow-up papers. PHOEBE is released under the GNU General Public License,
which guarranties it to be free, open to anyone interested to join in on future
development.
