Disney has a system called Fast Pass. Nobody wants to wait in long lines and Disney has come up with a solution to it. Kiosks in front of many popular rides have a place to insert your park pass. When you do, you get a ticket that gives you a time frame in which to return to the ride and go in the Fast Pass lane. This line moves much faster than the regular line.
You can only get one fast pass at a time but there is a secret to "working" the Fast Pass system. Many people don't realize that if you come back to the ride after the time frame given, they will still honor the Fast Pass. So if your Fast Pass is for the time frame of 1:20 to 2:30 and you come back at 4:30, they will still honor your fast pass. As long as you use the pass that day, they'll honor it. On the other end, you cannot use your Fast Pass earlier than the beginning time. If you arrive at 1:19, they'll make you wait till 1:20. Here's how we work the Fast Pass system: We'll use the Magic Kingdom as an example. We arrive in the morning and head to Splash Mountain, get a Fast Pass. Then go wait in the regular line at Pirates of the Carribbean (which usually moves pretty fast anyway!), once finished Pirates, it's usually time to use the Fast Pass we got for Splash Mountain. But before going on there, we go get another Fast Pass! Now you can only get another Fast Pass if you are within that time frame of your Fast Pass. So using that same Fast Pass time frame example above of 1:20 -2:30, if it's past 1:20, you can get another Fast Pass, regardless of whether you used the first one. It's a little confusing till you learn how to use it and there are some people who just never use it because they don't understand it, but I highly recommend getting acquainted with that system and using it because you'll get on many more rides that way. One thing to remember is that sometimes during busy seasons in the parks, by mid-afternoon, Fast Passes are no longer available for some extremely popular rides such as Soarin over California in Epcot. So if there's something you definitely want to go on in a certain park, get your Fast Pass as early as possible.