A great lesson from a great teacher

Rasgueado is a guitar finger strumming technique commonly associated with flamenco guitar music but also used in classical pieces. 
The rasgueado is executed using the fingers of right hand in rhythmically precise and rapid strumming patterns, using also the outer side of the fingernails.

In this video, Pepe Romero offers to his student some useful tips for a good rasgueado: