I need a little help understanding this concept, and if someone can help explain it to me, I would be very happy.

Basically I am trying to write a flash-based MUD. It will be pretty much a traditional mud except I want it to show images of places and some visual effects. Its mostly something I just wanted to do for fun.

Can someone explain to me the concept of how a flash based client can receive information from the server so it knows which picture to display, and visa versa, sending information back to the server?

If this is to vague, I'll try to explain it better, but right now I really can't think of any better way.