This is a great Disney tool for people with young children and/or children of different ages and abilities. Here is the direct info from Disney:
What Is Rider Switch and How Does It Work?
Rider Switch is available at select attractions at all 4 Walt Disney World Resort theme parks.
To Use Rider Switch:
1. First check with a Cast member to see if Rider Switch is offered at the attraction in question.
2. Once at the attraction, approach the greeting Cast Member with your entire party. At least one adult member of your party and the Guests who are not riding will be given a Ride Switch pass and asked to wait in a designated area (usually outside of the attraction). This group is “Party 2.”
3. The other party members (“Party 1”) ride the attraction.
4. After riding the attraction, Party 1 locates Party 2 and gives the Rider Switch pass to the adult member who will be riding. Party 1 takes over supervision of the non-riding children or Guests.
5. Party 2 enters and boards the attraction without having to wait in the regular queue a second time. The Rider Switch Pass must be presented to a Cast Member at this time.
If the person in Party 2 waited alone with the child, he or she may bring one other Guest back to ride the attraction with him or her. Please note that only 2 Guests are allowed per Rider Switch Pass.