List and describe two styles of music composition that developed during the twentieth century.

Two types of music composition developed during the 20th century:  
Rock-N-Roll - an evolution of rhythm and blues which relied heavily on electric instruments. Often dominated by heavy use of electric guitars in particular.   
and Rap - a rhyming chant accompanied by rhythmic music. Often associated with derogatory lyrics and misogynistic undertones.

Answer squarcialupi codex;