The best place to find a basic explanation of Fastpass is the official Disneyland webpage. While it sounds straightforward, there are some tips and tricks that will help you get the most out of Fastpass, and like anything at a Disney theme park, it’s always changing.
The Fastpass machines in each park function like a network. When a guest attempts to get a Fastpass by inserting admission media into the barcode reader, the machine does two things: First it checks to see if you already have a valid Fastpass for the same attraction (that is, a Fastpass with a start time later than the current time). If you don't have one, it then checks to see if you have a current Fastpass for another attraction on the same network (Fastpass attractions at Disneyland and Disney California Adventure are completely separate). The ticket or pass you use to obtain the Fastpass must have been used to enter the theme park prior to insertion into the machine; you can’t send one person into a park with a pile of tickets while the rest of your party has breakfast.
Understanding the rules for what makes a Fastpass current at an attraction is essential to getting full use out of the system. When you receive a Fastpass for Attraction A, you will not be able to get a Fastpass at Attraction B until either 1) the starting time of the Attraction A Fastpass has passed, or 2) two hours have passed since the Attraction A Fastpass was issued. If you examine the bottom of the valid Fastpass you are holding, it will state "Another Fastpass will be available at XX:XX." After that time has passed, you can then get another Fastpass for an additional attraction. You must use a Fastpass within the listed time window.
Fastpass tickets are distributed for increasing return times until all time slots for the day have been filled. For popular attractions or during peak periods, Fastpass distribution may close early in the day, so it is best to obtain them as soon as you can after entering.
Fastpass machines are turned off if an attraction experiences a temporary closure and are turned back on when the attraction returns to normal operation.
Currently, the Fastpass attractions in each park at Disneyland Resort are:
Disney California Adventure
The World of Color Fastpass tickets are distributed from the Grizzly River Run machines in the morning on the same day as that evening’s performances. Distribution continues until all tickets have been issued, or Disneyland makes the decision to cut them off.
Historically, some Fastpass attractions have been disconnected from the network, and are sometimes referred to as “standalone” attractions. That means that you could hold the Fastpass for these attractions, and still get a Fastpass for another attraction before you would normally be eligible to receive one. Currently there is only one machine that is disconnected:
Additionally, there are a few Fastpass attractions that operate only on weekends, or on weekdays during peak and holiday periods. However, if crowds are low, it’s not likely that you would need a Fastpass for those attractions.
The Times Guide handed out at the entrance turnstiles and other locations inside the park will list the Fastpass attractions for that day. However, you will still need to confirm it at the actual attraction, as this is subject to change.
Before you use a Fastpass at an attraction, get a new Fastpass for that same attraction if you intend to ride it again that same day. This action will optimize your return time and avoid any changes that might occur, including shut down of the Fastpass machines, while you are in the queue or riding the attraction.
Another option is to get a new networked Fastpass prior to using one that has reached its return time window. For example, you have an Indiana Jones Adventure Fastpass with a return time of 1:35 p.m. At 1:35, you could get a Splash Mountain Fastpass (with a return time of 4:50 to 5:50 p.m.) and then go back to ride Indiana Jones Adventure. Then at 3:35 pm (don't forget the two-hour rule), you could pick up a Big Thunder Mountain Railroad Fastpass before riding Splash Mountain. Continuing this pattern throughout the day will ensure that you maximize your Fastpass advantage.
At any given time a regular Fastpass user could possibly hold one Fastpass for each standalone attraction plus one or two of the networked attractions in each park, depending on return times in relation to the two-hour rule.
Another thing to think about to maximize the number of rides you get in a day are the attractions with single-rider lines: Splash Mountain, Goofy’s Sky School, Grizzly River Run, Soarin' Over California, Radiator Springs Racers and California Screamin'. With the exception of Soarin' Over California, use of single-rider lines is generally faster than Fastpass, so if you are willing to ride solo you can use Fastpass for any of the other attractions.