Yesterday we began using some dog show equipment with the puppies. We started small and introduced them to the stacking block. This is a simple instrument that allows a handler to teach a proper stack to a dog. This is the behavior in which the dog stands in the proper position for the written standard for his breed.
Swaying the puppy helps to calm them 
Gently placing them on the stacking block 
Positioning their little feet 
Finishing with the Portie Over back Tail position
A good video to watch is produced by Sandollar Aussies. Piper, the handler shown in the images here, has worked with Sandollar Aussies and credits their teaching as a part of her current success in the breed ring.
What you are seeing in the images is considered Hand Stacking, This is done for a judge’s examination when in the show ring. There is also a term/behavior called a Free Stack where the handler does not put their hands on the dog. This is encouraged through body language of the handler interacting with the dog.
We also train a Show Stack that is part of the Puppy Culture training program we employ. This “stacking” and “not sitting” behaviors are an example of what PC calls Behavior Homophones. The two behaviors look similar as the dogs are both “standing,” but in reality they could not be more different. … And “Stacking” is a MUCH more direct route to a dog who shows as if he owns the ground he stands on.