ISR physics at BABAR

A method of measuring e+e- annihilation cross sections at low energy sqrt{s}< 5 GeV, using initial-state radiation, is described. Experimental data from the PEP-II B-factory at 10.6 GeV center-of-mass energy, obtained via ISR, are presented. The cross sections are measured for many processes e+e- --> 3pi, 4pi, 2K pi, 2K 2pi, 4K, p anti-p, Lambda anti-Lambda, D anti-D, ... . From the measured cross sections the parameters of known resonances are improved, the baryons form factors are derived and compared with theory predictions. New states, e.g; Y(4260) and Y(2175), for which the internal structure is not yet established, are observed.