Out of all the eight forwards, the hooker is the one player with the most responsibility.
They have two very important roles to play.
Their first duty is to hook the ball for the scrum-half to collect in the scrum.
And their second is to throw the ball in at the line-outs for the jumpers to catch.
This is often done under intense pressure - so hookers need plenty of nerve and confidence.
Like props, hookers need to have a strong back and neck, as well as powerful arms and legs.
But they need to be that bit more flexible than their fellow front row mates because they are the ones who hook the ball in the scrum.
Hookers are often the smallest member of the forwards, but that doesn't mean they are the least important.