Model Deforms When I move A Bone When I parented my rig to my model with automatic weights. The model deforms when I try to pose it. The arm bone attaches to the leg and pulls with it. 

EXAMPLE: http://i.imgur.com/mdQnlbH.png

(please note: Im rather new to rigging in BLENDER)
The automatic weights aren't perfect, you can manually decide what part of the mesh gets to be controlled by what bone.

It's called weight painting.

Here is a tutorial for beginners.