Oral tradition is an integral part of nearly every culture worldwide, and poetry is very much a part of that tradition. The power of the spoken word is, as the proverb states, impenetrable. But the way in which that word is being spoken is changing. There's a lot of moving around, there's usually not a podium.
Slams are interactive - the crowd's response is a big factor.
The audience is free to shout out if they are so moved. Slam delivery is often theatrical and musical. Poetry does not become truly real until it is given breath. The evolution of the poetry slam as an art form reflects a desire for an accessible method of expression - one which allows artists to freely voice their words to today's jaded audiences. Slam's roots lie initially in hip-hop and ultimately in jazz, blues, improv and theater.