Progress on the potential method, recently proposed to investigate hadron
interactions in lattice QCD, is reviewed. The strategy to extract the potential
in lattice QCD is explained in detail. The method is applied to extract NN
potentials, hyperon potentials and the meson-baryon potentials. A theoretical
investigation is made to understand the origin of the repulsive core using the
operator product expansion. Some recent extensions of the method are also
discussed.Comment: 52 pages, 65 figures, Review to appear in "Progress in Particle and
Nuclear Physics