Purge?

Hey guys, i have a 1988 oldsmobile cutlass ciera and I was doing some work on it the other day and I realized a little rubber tube coming out of a small black box. the box said purge on it and the rubber tube was connected to this box on one end and to nothing on the other end. Now i tried reading up on what this is for exactly but could not find out what the just of it is or if it is supposed to be hooked up to anything else. After looking around the car for a bit i saw that another rubber tube (this one was coming out of the engine) and they seemed to fit into each other. Im not sure if its just a coincidence or if they do belong attached. I realize that it most obviously is that but I would like to learn what this purge does exactly and be certain that it connects to the engine, thanks alot for your time

Matt