  Basic idea of Randall-Sundrum brane world model I and II is reviewed with
detailed calculation. After introducing the brane world metric with exponential
warp factor, metrics of Randall-Sundrum models are constructed. We explain how
Randall-Sundrum model I with two branes makes the gauge hierarchy problem much
milder, and then derive Newtonian gravity in Randall-Sundrum model II with a
single brane by considering small fluctuations.
