The fly-half is the man who is responsible for implementing the game plan.
There is a lot of responsibility on his shoulders because of that.
Whether it is by kicking or passing, the fly-half is centrally involved in the game for a large part of the 80 minutes.
The best fly-halves in the world can kick, pass and read the game.
David Humphreys facts
Born: 10 September 1971, Belfast
Height: 5ft 10in
Tackling is becoming a big part of the responsibilities of a fly-half as well.
Communication with the backs and forwards is important too when it comes to carrying out the game plan.
A lot of work put in during training will mean that communication becomes second nature.
The fly-half tends to be one of the smaller members of the team. But size isn't that important, it's the skills that matter.
Not all fly-halves are the goal kickers on their teams but because I am, that is one skill that I practice regularly.
A major part of the game is kicking from the hands and it's important to put some work into developing that part of your game.
Jonny Wilkinson is regarded as one of the best fly-half around and he is able to do everything that is needed in the position.
That is the level that all other players who play in his position want to achieve, even players like me.
He is definitely the best fly-half I have ever faced.