Here's as good a definition as any I've seen:
"So look…so here’s what we know, okay? We know who we are as Democrats and we know what Democrats believe. First of all at home, we believe in equal opportunity for every single American regardless of race, color, ethnicity, sexual orientation, gender or any other distinguishing or non-distinguishing feature. <applause> We believe every American has a voice. That’s what we stand for. <applause> We believe we’ve got to have a strong economy and that means we’ve got to have a better business environment founded on strong educational systems and strong health systems that help every American live up to his or her full potential. <applause> We believe we have to have a strong national defense and we support the men and women in uniform but we also know that America’s national security is best protected not by building fences around America but by building bridges across differing nations and bringing people together, not tearing them apart. <applause>"
http://www.securingamerica.com/printready/clarkcast_061806.htm