Fast Passes - most of the major attractions have these now. Look for the Fast Pass Distribution machines which are near the entrance to the rides. Insert your Park Entry ticket and you will be given a Fast Pass ticket. You need to do this for everyone who wants to ride, using a different Park Entry ticket for each Fast Pass needed. The Fast pass ticket will have a time slot printed on, for example 11.20-11.50. You can then return at any time during that slot, look for the Fast Pass Return queue, show the Cast member your Fast Pass and head on up to the ride. There may still be a queue, but it will be fast moveing and much shorter than the Standby queue (which is what they call the non-FP queue!)
You can only hold one FP per Entry Park ticket at any time. E.g. if you get a FP for Big Thunder Mountain, you can't then just wander across to Splash Mountain and get another one immediately. This stops people just stockpiling a load of FPs all at once. Your FP ticket will tell you when your next FP can be collected, eg if your return slot for Big Thunder Mountain is 11.20-11.50, it may say 'Next FP available from 11.25'; you could then collect a FP for Splash Mountain at 11.25 before riding BTM at 11.30....phew!
Hope this makes sense. Sorry for long reply, but you did ask! Any more advice needed, just say, I'm a WDW fan as you may have guessed!