What do sheepdogs actually DO?
Well, basically, a good sheepdog should do most of the sheep gathering, handling and driving work for the shepherd or farmer.
I remember watching a very proud owner of a Huntaway trying to convince me that she didn't need a "gathering" sheepdog because the Huntaway would drive the sheep into the far corner of her large field and she would walk across the field, put the dog on a long lead, and dog and woman would then chase the sheep around the field until they went out through the gate, down the drive, into the yard. From there, they were easily driven into the shed.
I resisted the temptation to demonstrate that I could have stood by the shed while my dog went and fetched the sheep from the field, down the lane and into the yard by herself.
It'll seem obvious to many, but a sheepdog should move around sheep without disturbing them unduly. He should have the "power" to bring or drive them wherever you want him to without unduly stressing or damaging them in any way. Sheepdog Power is a thing we'll discuss later.
In the UK and many other countries of the world, a good sheepdog is expected to leave the shepherd or farmer's side and go out to gather the sheep in a "pear shaped" outrun (widening as it gets nearer the sheep) and then bringing them quietly and efficiently to the handler.
There are (of course) many other tasks the sheepdog performs, such as driving, penning, holding and pushing sheep through a "race" but the primary function is usually the outrun and bringing the sheep to the handler.