In short, says futurist and social analyst Marian Salzman, it is the universe of social networking itself, simply pushed into the real world.
"It's a new kind of social," says Ms. Salzman. Younger travelers "want to see the world in the way they live now, which is totally connected, with hundreds of casual friends."
It's a powerful, word-of-mouth way to make connections with people all over the world, says Cameron Siewert, content manager for the online travel site, IgoUgo.com. And it makes travel accessible in a way it hasn't been before.
Adventurous types have always relied on the sofas of strangers, she adds, but now, "the serendipity of this kind of spontaneous contact can actually be done ahead of time."
For the uninitiated, this headlong embrace of the unknown seems as though it would be rife with problems, most prominently safety concerns. And certainly there are cautionary tales: The American college student who couch surfed with a website member in Italy and was sexually attacked, not to mention the Norwegian travel mooch who couldn't seem to find another place to go after he landed on the divan of a student at the University of California at Berkeley.