The scrum-half's basic role is to deliver the ball from the base of the scrum, ruck or maul to spark the backline, but that is too simplistic and ignores hundreds of other key characteristics.
The traditional skills of passing and kicking are obviously important and you need a broad range of those skills.
A scrum-half needs to be able to deliver the ball not just from the base but however it comes at him, whether that is over the head or through the legs.
And kicking is not just all about the traditional box kick. It's little grubbers along the floor, or long punts or quick tap penalties.
You have to understand when to make breaks and when to pass
Other elements such as defence, organising how the forwards links with the backs, man-management, decision-making, staying on your feet and minimising your time at the bottom of rucks also make up the scrum-half armoury.
But one of the most important attributes of a good scrum-half is a natural instinct and confidence, though sadly these are quite often coached out of players in favour of the basics.
I don't mean you have to be a fantastic public speaker or have that first-on-the-dancefloor confidence. It's about being confident in your understanding of how the team are trying to play and being able to implement those ideas as an individual.
If a scrum-half just shovels the ball out time and again, he isn't a threat and as soon as he's not a threat, the focus of the opposition back row and inside backs goes on the fly-half.
Good scrum-halves like Scotland's Mike Blair and Chris Cusiter and Wales' Dwayne Peel have all the traditional skills but you can't take your eyes off them for a moment because if you do, they're through the gap and gone and they've got the pace to finish.
Having that threat creates more room for their own backline because the opposition back row have to check for a split-second to see what they might have up their sleeves.
But you have to understand when to make breaks and when to pass and that comes from instinct and experience.