Rational Curves on Varieties
  The aim of these notes is to give a introduction to the ideas and techniques of handling rational curves on varieties. The main emphasis is on varieties with many rational curves which are the higher dimensional analogs of rational curves and surfaces.   The first six sections closely follow the lectures of J. Koll\'ar given at the summer school ``Higher dimensional varieties and rational points''. The notes were written up by C. Araujo and substantially edited later. Revised version with 2 new sections. 
Carolina Araujo (Princeton Univ), J\'anos Koll\'ar (Princeton Univ)