The number 8's duties are similar to his loose forward team-mates - to tackle, carry and provide the backs support in breaks.
But he also has the added responsibility of securing possession at the base of the scrum.
The number 8 should have a psychological advantage over the opposing scrum-half, the little guys who are like big roosters!
Former South Africa scrum-half Joost van der Weisthuizen was a classic. He would come up to you at the back of a scrum and say 'I'm going to get this ball off you' - well, that's one of the nicer things he would say!
A number 8 has such an important role to release wingers, the fly-half and full-back.
Personally I don't think enough teams use the base of the scrum as an attacking option in the modern game.
You don't necessarily have good footballing skills, but you have to have a good awareness of creating space.
When you're looking at the ball at the base of the scrum you must have that innate sense of position, of knowing where your team-mates are.