PLL is used in the fridrich method. It permutes the pieces of the last layer, after they are oriented with OLL. There are 21 PLL cases, which all have their own algorithm. In the pictures below are the possible situations shown. Note that you can better pay attention to the arrows, since the colours only show one of the four possible situations. The blue arrows indicate movements of cornerpieces, while the red arrows indicate movements of edgepieces. All algorithms are from www.cubewhiz.com.
The algorithms may look a little cryptic, because the advanced notation is used.