a1 Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
a2 Kapteyn Astronomical Institute, PO Box 800, 9700AV Groningen, The Netherlands
We first review the nonrelativistic Lagrangian theory as a framework for the MOND equation. Obstructions to a relativistic version of it are discussed leading up to TeVeS, a relativistic tensor-vector-scalar field theory which displays both MOND and Newtonian limits. The whys for its particular structure are discussed and its achievements so far are summarized.
(Online publication May 19 2006)