Well, it's another fill-in talk by one of the organizers. The message is clear: we need talks! Please volunteer! We especially would like to hear from students.

That said, I do have some new understandings about the Parker's model of coronal heating based on a simple concept that we all learned from our statistical mechanics classes: random walk. In this talk, I will review the coronal heating problem and what we have done on it in numerical simulations. I hope to show how we can understand these results theoretically, based on the concept of random walk of the magnetic field line footpoints on the photosphere (surface of the sun). I hope students will at least get this out of this talk: a simple concept like random walk we learned in our undergraduate studies can help understanding great unresolved problems in physics.