Fast pass allows you to "virtually" wait in line. It's very simply actually and when utilized, can really benefit the time you spend in the park. To use FP, you take your admission ticket that you used to get into DL and put it into one of the FP machines (located just outside of the attraction) and you will be issued a "return between this timeframe" ticket. You can then use you time while you "virtually wait in line" to do other things, such as visit less crowded attractions, shop, eat, etc. You then return to that attraction between the times stated on your FP and you bypass the normal standby line. You can obtain more then one FP too. After you have gotten your FP, say on Star Tours, you can obtain your next FP (at another attraction) two hours after the issue time, or after the return time stated on your Star Tours FP ticket (which ever occurs first). I usually tell folks that to optimize their FP usage, get your next FP prior to returning to your first FP location. For example, you get your FP on Mansion at 10am and your return time is 11:45am, wait until 11:45 and go get your next FP (say Splash) and then return to Mansion and ride it. This way, your next FP ride time is already set up. Please remember to get a FP ticket for each person in your party. Each rider must have their own FP ticket for entry. I have used FP when visiting with my family and were able to get many big tickets rides done in a rather small amount of time.