Can someone explain mailing lists?

Ok, I’m savvy about most technical communication mediums on the net, like IRC, usenet, email (duh!), and so on. But the concept of mailing lists evades me. I’ve joined them many times, but I have no clue what order messages were posted, how to ask a question, who sees the question, etc.

Have you ever used mailing lists? The reason I need to learn is because there are the best and brightest using the lists and I want access to them (this is for my iPhone development).