Astad Deboo - The Visuals of Modern Dance

Born in the early 20th century, modern dance is a dance style that centers on a dancer's own interpretations instead structured steps, as in traditional ballet dancing. During the 1900's, European dancers began rebelling against the rigid rules of classical ballet. Turning against the structured techniques, costumes and shoes of ballet, these dancers favaored a more relaxed, free style of dancing. Modern dance pioneers often danced in bare feet and revealing costumes. In the United States, several dance pioneers paved the way for American modern dance, including the legendary Martha Graham.

(From http://dance.about.com.)